A think tank or policy institute is a research institute which performs research and advocacy concerning topics such as social policy, political strategy, economics, military, technology, and culture. Most policy institutes are non-profit organisations, which some countries such as the United States and Canada provide with tax exempt status. Other think tanks are funded by governments, advocacy groups, or corporations, and derive revenue from consulting or research work related to their projects.^[1]

The following article lists global policy institutes according to continental categories, and then sub-categories by country within those areas. These listings are not comprehensive, given that more than 7,500 think tanks exist worldwide.^[2][3]

The Jixia Academy is an early ancestor of the modern think tank. Based on passages in the Records of the Grand Historian, the academy is generally credited to King Xuan and given a foundation date around 318 BC. The academy has been summarized as "the first time on record a state began to act as a patron of scholarship out of the apparent conviction that this was a proper function of the state".^[4]

According to historian Jacob Soll, the term "think tank" is modern, but "it can be traced to the humanist academies and scholarly networks of the 16th and 17th centuries."^[5] Soll notes that "in Europe, the origins of think tanks go back to the 800s, when emperors and kings began arguing with the Catholic Church about taxes. A tradition of hiring teams of independent lawyers to advise monarchs about their financial and political prerogatives against the church spans from Charlemagne all the way to the 17th century, when the kings of France were still arguing about whether they had the right to appoint bishops and receive a cut of their income."^[5] He also writes, independent "research teams became common in the late 16th and early 17th centuries, when states often depended on independent scholars and their expertise."^[5]

Several major current think tanks were founded in the 19th century. For instance, the Institute for Defence and Security Studies (RUSI) was founded in 1831 in London, as was the Fabian Society in 1884. The oldest American think tank, the Carnegie Endowment for International Peace, was founded in Washington, D.C. in 1910 by philanthropist Andrew Carnegie. Carnegie charged trustees to use the fund to "hasten the abolition of international war, the foulest blot upon our civilization."^[6] The Brookings Institution was founded shortly thereafter in 1916 by Robert S. Brookings and was conceived as a bipartisan "research center modeled on academic institutions and focused on addressing the questions of the federal government."^[7]

After 1945, the number of policy institutes increased, with many small new ones forming to express various issue and policy agendas. Until the 1940s, most think tanks were known only by the name of the institution. During the Second World War, think tanks were often referred to as "brain boxes"^[8] after the slang term for skull. The phrase "think tank" in wartime American slang referred to rooms where strategists discussed war planning. Later the term "think tank" was used to refer to organizations that offered military advice, such as the RAND Corporation, which was founded in 1946 as an offshoot of Douglas Aircraft and became an independent corporation in 1948.

For most of the 20th century, independent public policy institutes that performed research and provided advice concerning public policy were found primarily in the United States, with a much smaller number in Canada, the UK and Western Europe. Although think tanks existed in Japan for some time, they generally lacked independence, having close associations with government ministries or corporations. There has been a veritable proliferation of "think tanks" around the world that began during the 1980s as a result of globalization, the end of the Cold War, and the emergence of transnational problems. Two-thirds of all the think tanks that exist today were established after 1970 and more than half were established since 1980.^[9]

The effect of globalisation on the proliferation of think tanks is most evident in regions such as Africa, Eastern Europe, Central Asia, and parts of Southeast Asia, where there was a concerted effort by the international community to assist in the creation of independent public policy research organizations. A recent survey performed by the Foreign Policy Research Institute's Think Tanks and Civil Societies Program underscores the significance of this effort and documents the fact that most of the think tanks in these regions have been established during the last 10 years. Presently there are more than 4,500 of these institutions around the world. Many of the more established think tanks, having been created during the Cold War, are focused on international affairs, security studies, and foreign policy.^[9]

Think tanks vary by ideological perspectives, sources of funding, topical emphasis and prospective consumers.^[10] Some think tanks, such as The Heritage Foundation, which promotes conservative principles, and the Center for American Progress are more partisan in purpose. Others, including the Tellus Institute, which emphasizes social and environmental topics, are more issue-oriented groups.

Funding sources and the consumers intended also define the workings of think tanks. Some receive direct government assistance, while others rely on private individual or corporate donors. This will invariably affect the degree of academic freedom within each policy institute and to whom or what the institution feels beholden. Funding may also represent who or what the institution wants to influence; in the United States, for example, "Some donors want to influence votes in Congress or shape public opinion, others want to position themselves or the experts they fund for future government jobs, while others want to push specific areas of research or education."^[10]

A new trend, resulting from globalization, is collaboration between policy institutes in different countries. For instance, the Carnegie Endowment for International Peace operates offices in Washington, D.C., Beijing, Beirut, Brussels and Moscow.^[10]

The Think Tanks and Civil Societies Program (TTCSP) at the University of Pennsylvania, led by Dr. James McGann, annually rates policy institutes worldwide in a number of categories and presents its findings in the "Global Go-To Think Tanks" rating index.^[11] However, this method of the study and assessment of policy institutes has been criticized by researchers such as Enrique Mendizabal and Goran Buldioski, Director of the Think Tank Fund, assisted by the Open Society Institute.^[12][13]

Several authors have indicated a number of different methods of describing policy institutes in a way that takes into account regional and national variations. For example:^[14]

Alternatively, one could use some of the following criteria:

In some cases, corporate interests^[27] and political groups have found it useful to create policy institutes, advocacy organizations, and think tanks. For example, The Advancement of Sound Science Coalition was formed in the mid-1990s to dispute research finding an association between second-hand smoke and cancer.^[28] According to an internal memorandum from Philip Morris Companies referring to the United States Environmental Protection Agency (EPA), "The credibility of the EPA is defeatable, but not on the basis of ETS [environmental tobacco smoke] alone,... It must be part of a larger mosaic that concentrates all the EPA's enemies against it at one time."^[29]

According to the Fairness and Accuracy in Reporting, both left-wing and right-wing policy institutes are often quoted and rarely identified as such. The result is that think tank "experts" are sometimes depicted as neutral sources without any ideological predispositions when, in fact, they represent a particular perspective.^[30][31] In the United States, think tank publications on education are subjected to expert review by the National Education Policy Center's "Think Twice" think tank review project.^[32]

A 2014 New York Times report asserted that foreign governments buy influence at many United States think tanks. According to the article: "More than a dozen prominent Washington research groups have received tens of millions of dollars from foreign governments in recent years while pushing United States government officials to adopt policies that often reflect the donors’ priorities."^[33]

Ghana's first president, Dr. Kwame Nkrumah, set up various state-supported think in the 1960s. By the 1990s, a variety of policy research centers sprang up in Africa set up by academics who sought to influence public policy in Ghana.

One such think tank was The Institute of Economic Affairs, Ghana, which was founded in 1989 when the country was ruled by the Provisional National Defence Council. The IEA undertakes and publishes research on a range of economic and governance issues confronting Ghana and Sub-Saharan Africa. It has also been involved in bringing political parties together to engage in dialogue. In particular it has organised Presidential debates every election year since the Ghanaian presidential election, 1996.

Notable think tanks in Ghana include:

According to the Global Go Think Tank Report 2012, there are 14 think tanks in Armenia, the majority of which are located in Yerevan.^[38] Notable think tanks in Armenia include the Economic Development and Research Center (EDRC) and International Center for Human Development (ICHD).

Bangladesh has a number of think tanks that are in the form of governmental, non-governmental and corporate organizations.

In the People's Republic of China a number of think tanks are sponsored by governmental agencies like Development Research Center of the State Council, but still retain sufficient non-official status to be able to propose and debate ideas more freely. In January 2012, the first non-official think-tank in China, South Non-Governmental Think-Tank, was established in the Guangdong province.^[39] In 2009 the China Center for International Economic Exchanges, described as "China's top think tank," was founded.

In Hong Kong, early think tanks established in the late 1980s and early 1990s focused on political development, including the first direct Legislative Council members election in 1991 and the political framework of "One Country, Two Systems," manifested in the Sino-British Joint Declaration. After the transfer of sovereignty to China in 1997, more think tanks were established by various groups of intellectuals and professionals. They have various missions and objectives including promoting civic education; undertaking research on economic, social and political policies; and promoting "public understanding of and participation in the political, economic, and social development of the Hong Kong Special Administrative Region".

Think tanks in Hong Kong include:

India has a number of think tanks.^[40] Most are based in New Delhi, and a few are government sponsored. A number of these work on foreign policy and security issues. There are a few think tanks like Observer Research Foundation and Centre for Civil Society who promote liberal, social and economic ideas, and others who encourage students to do empirical research and gain first hand experience in public policy issues..

In Mumbai, Strategic Foresight Group is a global think tank that works on issues such as Water Diplomacy, Peace and Conflict and Foresight (futures studies). Think tanks with a development focus include those like the National Centre for Cold-chain Development ('NCCD'), which serve to bring inclusive policy change by supporting the Planning Commission and related government bodies with industry-specific inputs – in this case set up at the behest of the government to direct cold chain development. Some think tanks have a fixed set of focus areas and they work towards finding out policy solutions to social problems in the respective areas.

Initiatives such as National e-Governance Plan (to automate administrative processes)^[41] and National Knowledge Network (NKN) (for data and resource sharing amongst education and research institutions), if implemented properly, should help improve the quality of work done by think tanks.^[42]

There are over 50 recently emerged think tanks in Iraq, particularly in the Kurdistan Region. Iraq's leading think tank is the Middle East Research Institute (MERI),^[43] based in Erbil. MERI is an independent non-governmental policy research organisation, established in 2014 and publishes in English, Kurdish and Arabic. It was listed in the global ranking by the USA's Lauder Institute of the University of Pennsylvania as 46th in the Middle East.^[44]

There are many think tank teams in Israel, including:^[45]

Japan has over 100 think tanks, most of which cover not only policy research but also economy, technology and so on. Some are government related, but most of the think tanks are sponsored by the private sector.

Most Malaysian think tanks are related either to the government or a political party. Historically they focused on defense, politics and policy. However, in recent years, think tanks that focus on international trade, economics and social sciences have also been founded.

Notable think tanks in Malaysia include:

Pakistan's think tanks mainly revolve around social policy, internal politics, foreign security issues, and regional geo-politics. Most of these are centered on the capital, Islamabad. One notable think tank is the Sustainable Development Policy Institute (SDPI), which focuses on policy advocacy and research particularly in the area of environment and social development. Another notable policy research institute based in Islamabad is the Institute of Social and Policy Sciences (I-SAPS) which works in the fields of education, health, disaster risk reduction, governance, conflict and stabilization.

Think tanks in the Philippines could be generally categorized in terms of their linkages with the national government. Several were set up by the Philippine government for the specific purpose of providing research input into the policy-making process.^[48]

Sri Lanka has a number of think tanks that are in the form governmental, non-governmental and corporate organizations.

There are several think tanks in Singapore that advise the government on various policies and as well as private ones for corporation within the region. Many of them are hosted within the local public educational institutions.

Among them are the Singapore Institute of International Affairs (SIIA), Institute of Southeast Asian Studies (ISEAS), and the S. Rajaratnam School of International Studies.^[49]

The UAE has been a center for political oriented think tanks which concentrate on both regional and global policy. Notable think tank have emerged in the global debate on terrorism, education & economical policies in the MENA region. Think tanks include:

Key projects: Preparation of the National human development report for Uzbekistan, Sociological "portrait" of the Uzbek businessman, Preparation of an analytical report on export procedures optimization in Uzbekistan, various industry and marketing researches in Uzbekistan, Tajikistan, and Turkmenistan.

In 2017 Taiwan had 58 think tanks, the 25th most in the world.^[51] Like in most countries there is a mix of government funded and privately funded Think Tanks.^[52]

Taiwanese think tanks in alphabetical order:

Most Australian think-tanks are based at universities – for example, the Melbourne Institute – or are government-funded – for example, the Productivity Commission or the CSIRO.

Private sources fund about 20 to 30 "independent" Australian think tanks. The best-known of these think tanks play a much more limited role in Australian public and business policy-making than do their equivalents in the United States. However, in the past decade the number of think tanks has increased substantially. Prominent Australian conservative think tanks include the Centre for Independent Studies, the Sydney Institute and the Institute of Public Affairs. Prominent leftist Australian think tanks include the McKell Institute, Per Capita, the Australia Institute, the Lowy Institute and the Centre for Policy Development. In recent years regionally-based independent and non-partisan think tanks have emerged. Some, such as the Illawarra's i-eat-drink-think, engage in discussion, research and advocacy within a broader civics framework. Commercial think-tanks like the Gartner Group, Access Economics, the Helmsman Institute, and others provide additional insight which complements not-for-profit organisations such as CEDA, the Australian Strategic Policy Institute, and the Australian Institute of Company Directors to provide more targeted policy in defence, program governance, corporate governance and similar.

Listed in alphabetical order, think tanks based in Australia include:

Think tanks based in New Zealand include:

Brussels hosts most of the European Institutions, hence a large number of international think tanks are based there. Notable think tanks are Bruegel, the Centre for European Policy Studies (CEPS), Centre for the New Europe (CNE), the European Centre of International Political Economy (ECIPE), the European Policy Centre (EPC), the Friends of Europe, the Global Governance Institute (GGI), Liberales, and Sport and Citizenship, among others.

Bulgaria has a number of think tanks providing expertise and shaping policies, including Institute of Modern Politics.

Finland has several small think tanks that provide expertise in very specific fields. Notable think tanks include:

In addition to specific independent think tanks, the largest political parties have their own think tank organizations. This is mainly due to support granted by state for such activity. The corporate world has focused their efforts to central representative organization Confederation of Finnish Industries, which acts as think tank in addition to negotiating salaries with workers unions. Furthermore, there is the Finnish Business and Policy Forum (Elinkeinoelämän valtuuskunta, EVA). Agricultural and regional interests, associated with The Central Union of Agricultural Producers and Forest Owners (Maa- ja metsätaloustuottajain Keskusliitto, MTK) and the Centre Party, are researched by Pellervo Economic Research (Pellervon taloustutkimus, PTT). The Central Organisation of Finnish Trade Unions (Suomen Ammattiliittojen Keskusjärjestö, SAK) and the Social Democratic Party are associated with the Labour Institute for Economic Research (Palkansaajien tutkimuslaitos, PT). Each of these organizations often release forecasts concerning the national economy.

The French Institute of International Relations (IFRI) was founded in 1979 and is the third oldest think tank of western Europe, after Chatham House (UK, 1920) and the Stockholm International Peace Research Institute (Sweden, 1960). The primary goals of IFRI are to develop applied research in the field of public policy related to international issues, and foster interactive and constructive dialogue between researchers, professionals, and opinion leaders. France also hosts the European Union Institute for Security Studies (EUISS), a Paris-based agency of the European Union and think tank researching security issues of relevance for the EU. There are also a number of pro-business think tanks, notably the Paris-based Fondation Concorde.^[59] The foundation focuses on increasing the competitiveness of French SME's and aims to revive entrepreneurship in France.

On the left, the main think tanks in France are the Fondation Jean Jaures, which is organizationally linked to the French Socialist Party, and Terra Nova. Terra Nova is an independent left-leaning think tank, although it is nevertheless considered to be close to the Socialists. It works on producing reports and analyses of current public policy issues from a progressive point of view, and contributing to the intellectual renewal of social democracy.

Only French Think Tank mentioned in the list "Think Tank to watch" of the 2014 2014 Global Go To Think Tank Index Report^[60] GenerationLibre is a French think-tank created by Gaspard Koenig in 2013, independent from all political parties, which aims at promoting freedoms in France, in terms of fundamental rights, economics and societal issues. GenerationLibre is described as being able to connect to the right on pro business freedom and regulations issues but also to the left on issues such as basic income, gay marriage and the legalization of marijuana.

In Germany all of the major parties are loosely associated with research foundations that play some role in shaping policy, but generally from the more disinterested role of providing research to support policymakers than explicitly proposing policy. These include the Konrad-Adenauer-Stiftung (Christian Democratic Union-aligned), the Friedrich-Ebert-Stiftung (Social Democratic Party-aligned), the Hanns-Seidel-Stiftung (Christian Social Union-aligned), the Heinrich-Böll-Stiftung (aligned with the Greens), Friedrich Naumann Foundation (Free Democratic Party-aligned) and the Rosa Luxemburg Foundation (aligned with Die Linke).

The German Institute for International and Security Affairs is a foreign policy think tank. Atlantic Community is an independent, non-partisan and non-profit organization set up as a joint project of Atlantische Initiative e.V. and Atlantic Initiative United States. The Institute for Media and Communication Policy deals with media-related issues. Transparency International is a think tank on the role of corporate and political corruption in international development.

In Greece there are many think tanks, also called research organisations or institutes.

While think tanks are not widespread in Latvia, as opposed to single issue advocacy organizations, there are several noticeable institutions in the Latvian think tank landscape:

There are several think tanks that are established and operate under the auspices of Universities, such as:

All major political parties in the Netherlands have state-sponsored research foundations that play a role in shaping policy. The Dutch government also has its own think tank: the Scientific Council for Government Policy. The Netherlands furthermore hosts the Netherlands Institute of International Relations Clingendael, or Clingendael Institute, an independent think tank and diplomatic academy which studies various aspects of international relations.

There is a large pool of think-tanks in Poland on a wide variety of subjects. The oldest state-sponsored think tank is The Western Institute in Poznań (Polish: Instytut Zachodni). The second oldest is the Polish Institute of International Affairs (PISM) established in 1947. Another notable state-sponsored think tank is the Centre for Eastern Studies (OSW), which specializes in the countries neighboring Poland and in the Baltic Sea region, the Balkans, Turkey, the Caucasus and Central Asia. Among the private think tanks notable organizations include the Institute for Structural Research (IBS) on economic policy, The Casimir Pulaski Foundation on foreign policy, the Institute of Public Affairs (ISP) on social policy, and the Sobieski Institute.

Founded in 1970, the SEDES is one of the oldest Portuguese civic associations and think tanks. Contraditório think tank was founded in 2008. Contraditório is a non-profit, independent and non-partisan think tank.

The Romanian Academic Society (SAR), founded in 1996, is a Romanian think tank for policy research.

The Foundation for the Advancement of Economics (FREN) was founded in 2005 by the Belgrade University's Faculty of Economics.

Besides the international think tanks present in the surrounding countries as well (with Open Society Foundations being the most notable one) Slovakia has a host of its own think tanks as well. Some of the think tanks in Slovakia focus on public policy issues, such as Institute of Public Affairs (Inštitút pre verejné otázky or IVO in Slovak) or Central European Labour Studies Institute (Stredoeurópsky inštitút pre výskum práce or CELSI in Slovak). Others specialize on human rights issues such as minority protection, for example Forum Minority Research Institute (Fórum Kisebbségkutató Intézet or Fórum Intézet in Hungarian and Fórum inštitút pre výskum menšín or Fórum inštitút in Slovak). Since some of the Slovak think tanks are perceived to be associated with right-wing and liberal parties of Slovakia (with the perception being particularly strong among Slovak nationalists),^[65] findings and proposals made by these organizations are generally resented or ignored by left-wing supporters and nationalists.^[66]

The Elcano Royal Institute was created in 2001 following the example of the Royal Institute of International Affairs (Chatham House) in the UK, although it is closely linked to (and receives funding from) the government in power.

More independent but clearly to the left of the political spectrum are the Centro de Investigaciones de Relaciones Internacionales y Desarrollo (CIDOB) founded in 1973; and the Fundación para las Relaciones Internacionales y el Diálogo Exterior (FRIDE) established in 1999 by Diego Hidalgo and main driving force behind projects such as the Club de Madrid, a group of democratic former heads of state and government, the Foreign Policy Spanish Edition and DARA (international organization).

Former Prime Minister José Maria Aznar presides over the Fundación para el Analisis y los Estudios Sociales (FAES), a policy institute that is associated with the conservative Popular Party (PP). Also linked to the PP is the Grupo de Estudios Estratégicos (GEES), which is known for its defense- and security-related research and analysis. For its part, the Fundación Alternativas is independent but close to left-wing ideas. The Socialist Partido Socialista Obrero Español (PSOE) created Fundación Ideas in 2009 and dissolved it in January 2014. Also in 2009, the centrist Union, Progress and Democracy (UPyD) created Fundación Progreso y Democracia (FPyD).

Timbro is a free market think tank and book publisher based in Stockholm.

Think tanks based within Switzerland include:

There are more than 100 registered think tanks in Ukraine. For example:

In Britain, think tanks play a similar role to the United States, attempting to shape policy, and indeed there is some cooperation between British and American think tanks. For example, the London-based think tank Chatham House and the Council on Foreign Relations were both conceived at the Paris Peace Conference, 1919 and have remained sister organisations.

The Bow Group, founded in 1951, is the oldest centre-right think tank and many of its members have gone on to serve as Members of Parliament or Members of the European Parliament. Past chairmen have included Conservative Party leader Michael Howard, Margaret Thatcher's longest-serving Cabinet Minister Geoffrey Howe, Chancellor of the Exchequer Norman Lamont and former British Telecom chairman Christopher Bland.

CIVITAS, Demos, the Institute for Public Policy Research, Policy Exchange and Reform are five of the most significant think-tanks of the United Kingdom.

According to research done by the University of Pennsylvania, there are a total of 12 think tanks in Azerbaijan.

The Center for Economic and Social Development, or CESD; in Azeri, Azerbaijan, İqtisadi və Sosial İnkişaf Mərkəzi (İSİM) is an Azeri think tank, non-profit organization, NGO based in Baku, Azerbaijan. The Center was established in 2005. CESD focuses on policy advocacy and reform, and is involved with policy research and capacity building.

The Economic Research Center (ERC) is a policy-research oriented non-profit think tank established in 1999 with a mission to facilitate sustainable economic development and good governance in the new public management system of Azerbaijan. It seeks to do this by building favorable interactions between the public, private and civil society and working with different networks both in local (EITI NGO Coalition, National Budget Group, Public Coalition Against Poverty, etc.) and international levels (PWYP, IBP, ENTO, ALDA, PASOS, WTO NGO Network etc.).

The Center for Strategic Studies under the President of Azerbaijan is a governmental, non-profit think tank founded in 2007. It focusses on domestic and foreign policy.

According to the Foreign Policy Research Institute, Russia has 112 think tanks, while Russian think tanks claimed four of the top ten spots in 2011's "Top Thirty Think Tanks in Central and Eastern Europe".^[71]

Notable Russian think tanks include:

Turkish think tanks are relatively new. There are at least 20 think tanks in the country, both independent and supported by government. Many of them are sister organizations of political parties, universities or companies some are independent and others are supported by government. Most Turkish think tanks provide research and ideas, yet they play less important roles in policy making than American think tanks. Turksam, Tasam and the Journal of Turkish Weekly are the leading information sources.

The oldest and most influential think tank in Turkey is ESAM (The Center for Economic and Social Research; Turkmen: Ekonomik ve Sosyal Araştırmalar Merkezi) which was established in 1969 and has headquarters in Ankara. There are also branch offices of ESAM in Istanbul, Bursa, Konya and elsewhere. ESAM has strong international relationships, especially with Muslim countries and societies. Ideologically it performs policies, produces ideas and manages projects in parallel to Milli Görüş and also influences political parties and international strategies. The founder and leader of Milli Görüş, Necmettin Erbakan, was very concerned with the activities and brainstorming events of ESAM. In The Republic of Turkey, two presidents, four prime ministers, various ministers, many members of the parliament, and numerous mayors and bureaucrats have been members of ESAM. Currently the General Chairman of ESAM is Recai Kutan (former minister for two different ministries, former main opposition party leader, and founder and General Chairman of the Saadet Party).

The Turkish Economic and Social Studies Foundation (TESEV) is another leading think-thank. Established in 1994, TESEV is an independent non-governmental think-tank, analyzing social, political and economic policy issues facing Turkey. TESEV has raised issues about Islam and democracy, combating corruption, state reform, and transparency and accountability. TESEV serve as a bridge between academic research and policy-making. Its core program areas are democratization, good governance, and foreign policy.^[72]

Other notable Turkish think tanks are the International Strategic Research Organisation (USAK), the Foundation for Political, Economic and Social Research (SETA), and the Wise Men Center for Strategic Studies (BİLGESAM).

Canada has many notable think tanks (listed in alphabetical order). Each has specific areas of interest with some overlaps.

As the classification is most often used today, the oldest American think tank is the Carnegie Endowment for International Peace, founded in 1910.^[79] The Institute for Government Research, which later merged with two organizations to form the Brookings Institution, was formed in 1916. Other early twentieth century organizations now classified as think tanks include the Hoover Institution (1919), The Twentieth Century Fund (1919, and now known as the Century Foundation), the National Bureau of Economic Research (1920), the Council on Foreign Relations (1921), and the Social Science Research Council (1923). The Great Depression and its aftermath spawned several economic policy organizations, such as the National Planning Association (1934), the Tax Foundation (1937),^[80] and the Committee for Economic Development (1943).^[79]

In collaboration with the Douglas Aircraft Company, the Air Force set up the RAND Corporation in 1946 to develop weapons technology and strategic defense analysis.

More recently, progressive and liberal think tanks have been established, most notably the Center for American Progress and the Center for Research on Educational Access and Leadership (CREAL). The organization has close ties to former United States President Barack Obama and other prominent Democrats.^[81]

Think tanks help shape both foreign and domestic policy. They receive funding from private donors, and members of private organizations. By 2013, the largest 21 think tanks in the US spent more than $1 billion per year.^[82] Think tanks may feel more free to propose and debate controversial ideas than people within government. The progressive media watchgroup Fairness and Accuracy in Reporting (FAIR) has identified the top 25 think tanks by media citations, noting that from 2006 to 2007 the number of citations declined 17%.^[83] The FAIR report reveals the ideological breakdown of the citations: 37% conservative, 47% centrist, and 16% liberal. Their data show that the most-cited think tank was the Brookings Institution, followed by the Council on Foreign Relations, the American Enterprise Institute, The Heritage Foundation, and the Center for Strategic and International Studies.

Recently in response to scrutiny about think tanks appearing to have a "conflict of interest" or lack transparency, executive vice president, Martin S. Indyk of Brookings Institution – the "most prestigious think tank in the world"^[84] – admitted that they had "decided to prohibit corporations or corporate-backed foundations from making anonymous contributions." In August 2016, the New York Times published a series on think tanks that blur the line. One of the cases the journalists cited was Brookings, where scholars paid by a seemingly independent think tank "push donors' agendas amplifying a culture of corporate influence in Washington." For example, in exchange for hundreds of thousands of dollars the Brookings Institution provided the publicly-traded company Lennar Corporation – one of the United States' largest home builders – with a significant advantage in pursuing their $US8 billion revitalization project in Hunters Point, San Francisco. In 2014 Lennar's then-regional vice president in charge of the San Francisco revitalization, Kofi Bonner in 2014, was named as a Brookings senior fellow – a position as 'trusted adviser' that carries some distinction. Bruce Katz, a Brookings vice president, also offered to help Lennar Corporation "engage with national media to develop stories that highlight Lennar's innovative approach."^[84]

Government think tanks are also important in the United States, particularly in the security and defense field. These include the Center for Technology and National Security Policy at the National Defense University, the Center for Naval Warfare Studies at the Naval War College, and the Strategic Studies Institute at the U.S. Army War College.

The government funds, wholly or in part, activities at approximately 30 Federally Funded Research and Development Centers (FFRDCs). FFRDCs, are unique independent nonprofit entities sponsored and funded by the United States government to meet specific long-term technical needs that cannot be met by any other single organization. FFRDCs typically assist government agencies with scientific research and analysis, systems development, and systems acquisition. They bring together the expertise and outlook of government, industry, and academia to solve complex technical problems. These FFRDCs include the RAND Corporation, the MITRE Corporation, the Institute for Defense Analyses, the Aerospace Corporation, the MIT Lincoln Laboratory, and other organizations supporting various departments within the United States Government.

Similar to the above quasi-governmental organizations are Federal Advisory Committees. These groups, sometimes referred to as commissions, are a form of think tank dedicated to advising the US Presidents or the Executive branch of government. They typically focus on a specific issue and as such, might be considered similar to special interest groups. However, unlike special interest groups these committees have come under some oversight regulation and are required to make formal records available to the public. Approximately 1,000 these advisory committees are described in the FACA searchable database.^[85]

Research done by Enrique Mendizabal^[86] shows that South American think tanks play various roles depending on their origins, historical development and relations to other policy actors. In this study, Orazio Bellettini from Grupo FARO suggests that they:^[87]

How a policy institute addresses these largely depends on how they work, their ideology vs. evidence credentials, and the context in which they operate including funding opportunities, the degree and type of competition they have and their staff.

This functional method addresses the inherit challenge of defining a think tank. As Simon James said in 1998, "Discussion of think tanks...has a tendency to get bogged down in the vexed question of defining what we mean by ‘think tank’—an exercise that often degenerates into futile semantics."^[88] It is better (as in the Network Functions Approach) to describe what the organisation should do. Then the shape of the organisation should follow to allow this to happen. The following framework (based on Stephen Yeo's description of think tanks’ mode of work) is described in Enrique Mendizabal's blog "onthinktanks":

First, policy institutes may work in or base their funding on one or more of:^[89]

Second, policy institutes may base their work or arguments on:

According to the National Institute for Research Advancement, a Japanese policy institute, think tanks are "one of the main policy actors in democratic societies ..., assuring a pluralistic, open and accountable process of policy analysis, research, decision-making and evaluation".^[90] A study in early 2009 found a total of 5,465 think tanks worldwide. Of that number, 1,777 were based in the United States and approximately 350 in Washington DC alone.^[91]

Argentina is home to 122 think tanks; many specializing in public policy and economics issues, Argentina ranks fifth in the number of these institutions worldwide.^[92]

Working on public policies, Brazil hosts, for example, Instituto Liberdade, a University-based Center at Tecnopuc inside the Pontifícia Universidade Católica do Rio Grande do Sul, located in the South Region of the country, in the city of Porto Alegre. Instituto Liberdade is among the Top 40 think tanks in Latin America and the Caribbean, according to the 2009 Global Go To Think Tanks Index^[93] a report from the University of Pennsylvania's Think Tanks and Civil Societies Program (TTCSP).

Fundação Getulio Vargas (Getulio Vargas Foundation (FGV)) is a Brazilian higher education institution. Its original goal was to train people for the country's public- and private-sector management. Today it hosts faculties (Law, Business, Economics, Social Sciences and Mathematics), libraries, and also research centers in Rio, São Paulo and Brasilia. It is considered by Foreign Policy magazine to be a top-5 "policymaker think-tank" worldwide.

The Igarapé Institute is a Brazilian think tank focusing on public security and policing.