Capital controls are residency-based measures such as transaction taxes, other limits, or outright prohibitions that a nation's government can use to regulate flows from capital markets into and out of the country's capital account. These measures may be economy-wide, sector-specific (usually the financial sector), or industry specific (e.g. "strategic" industries). They may apply to all flows, or may differentiate by type or duration of the flow (debt, equity, or direct investment, and short-term vs. medium- and long-term).

Types of capital control include exchange controls that prevent or limit the buying and selling of a national currency at the market rate, caps on the allowed volume for the international sale or purchase of various financial assets, transaction taxes such as the proposed Tobin tax on currency exchanges, minimum stay requirements, requirements for mandatory approval, or even limits on the amount of money a private citizen is allowed to remove from the country. There have been several shifts of opinion on whether capital controls are beneficial and in what circumstances they should be used.

Capital controls were an integral part of the Bretton Woods system which emerged after World War II and lasted until the early 1970s. This period was the first time capital controls had been endorsed by mainstream economics. Capital controls were relatively easy to impose, in part because international capital markets were less active in general. In the 1970s, economic liberal, free-market economists became increasingly successful in persuading their colleagues that capital controls were in the main harmful.

The US, other Western governments, and multilateral financial institutions such as the International Monetary Fund (IMF) and the World Bank began to take a critical view of capital controls and persuaded many countries to abandon them to facilitate financial globalization.

The Latin American debt crisis of the early 1980s, the 1997 Asian financial crisis, the 1998 Russian financial crisis, and the 2008 financial crisis highlighted the risks associated with the volatility of capital flows, and led many countries, even those with relatively open capital accounts, to make use of capital controls alongside macroeconomic and prudential policies as means to dampen the effects of volatile flows on their economies.

In the aftermath of the 2008 financial crisis, as capital inflows surged to emerging market economies, a group of economists at the IMF outlined the elements of a policy toolkit to manage the macroeconomic and financial-stability risks associated with capital flow volatility. The proposed toolkit allowed a role for capital controls.

The study, as well as a successor study focusing on financial-stability concerns stemming from capital flow volatility, while not representing an IMF official view, were nevertheless influential in generating debate among policy makers and the international community, and ultimately in bringing about a shift in the institutional position of the IMF. With the increased use of capital controls in recent years, the IMF has moved to destigmatize the use of capital controls alongside macroeconomic and prudential policies to deal with capital flow volatility..

Prior to the 19th century, there was generally little need for capital controls due to low levels of international trade and financial integration. In the First Age of Globalization, which is generally dated from 1870 to 1914, capital controls remained largely absent.

Highly restrictive capital controls were introduced with the outbreak of World War I. In the 1920s they were generally relaxed, only to be strengthened again in the wake of the 1929 Great Crash. This was more an ad hoc response to potentially damaging flows rather than based on a change in normative economic theory. Economic historian Barry Eichengreen has implied that the use of capital controls peaked during World War II, but the more general view is that the most wide-ranging implementation occurred after Bretton Woods.

An example of capital control in the interwar period was the Reich Flight Tax, introduced in 1931 by German Chancellor Heinrich Brüning. The tax was needed to limit the removal of capital from the country by wealthy residents. At the time, Germany was suffering economic hardship due to the Great Depression and the harsh war reparations imposed after World War I. Following the ascension of the Nazis to power in 1933, the tax was repurposed to confiscate money and property from Jews fleeing the state-sponsored antisemitism.

At the end of World War II, international capital was caged by the imposition of strong and wide-ranging capital controls as part of the newly created Bretton Woods system—it was perceived that this would help protect the interests of ordinary people and the wider economy. These measures were popular as at this time the western public's view of international bankers was generally very low, blaming them for the Great Depression.

John Maynard Keynes, one of the principal architects of the Bretton Woods system, envisaged capital controls as a permanent feature of the international monetary system, though he had agreed current account convertibility should be adopted once international conditions had stabilised sufficiently. This essentially meant that currencies were to be freely convertible for the purposes of international trade in goods and services but not for capital account transactions. Most industrial economies relaxed their controls around 1958 to allow this to happen.

The other leading architect of Bretton Woods, the American Harry Dexter White, and his boss Henry Morgenthau, were somewhat less radical than Keynes but still agreed on the need for permanent capital controls. In his closing address to the Bretton Woods conference, Morgenthau spoke of how the measures adopted would drive "the usurious money lenders from the temple of international finance".

Following the Keynesian Revolution, the first two decades after World War II saw little argument against capital controls from economists, though an exception was Milton Friedman. From the late 1950s, the effectiveness of capital controls began to break down, in part due to innovations such as the Eurodollar market. According to Dani Rodrik, it is unclear to what extent this was due to an unwillingness on the part of governments to respond effectively, as compared with an inability to do so.

Eric Helleiner posits that heavy lobbying from Wall Street bankers was a factor in persuading American authorities not to subject the Eurodollar market to capital controls. From the late 1960s the prevailing opinion among economists began to switch to the view that capital controls are on the whole more harmful than beneficial.

While many of the capital controls in this era were directed at international financiers and banks, some were directed at individual citizens. In the 1960s, British individuals were at one point restricted from taking more than £50 with them out of the country for their foreign holidays. In their book This Time Is Different (2009), economists Carmen Reinhart and Kenneth Rogoff suggest that the use of capital controls in this period, even more than its rapid economic growth, was responsible for the very low level of banking crises that occurred in the Bretton Woods era.

According to Barry Eichengreen, capital controls were more effective in the 1940s and 1950s than they were subsequently.

By the late 1970s, as part of the displacement of Keynesianism in favour of free-market orientated policies and theories, and the shift from the social-liberal paradigm to neoliberalism countries began abolishing their capital controls, starting between 1973 and 1974 with the US, Canada, Germany, and Switzerland, and followed by the United Kingdom in 1979. Most other advanced and emerging economies followed, chiefly in the 1980s and early 1990s.

During the period spanning from approximately 1980–2009, the normative opinion was that capital controls were to be avoided except perhaps in a crisis. It was widely held that the absence of controls allowed capital to freely flow to where it is needed most, helping not only investors to enjoy good returns, but also helping ordinary people to benefit from economic growth. During the 1980s, many emerging economies decided or were coerced into following the advanced economies by abandoning their capital controls, though over 50 retained them at least partially.

The orthodox view that capital controls are typically harmful was challenged following the 1997 Asian financial crisis. Asian nations that had retained their capital controls such as India and China credited them for allowing them to escape the crisis relatively unscathed. Malaysia's prime minister Mahathir Mohamad imposed capital controls as an emergency measure in September 1998, including both strict exchange controls and limits on outflows from portfolio investments; these were found to be effective in containing the damage from the crisis.

In the early 1990s, even some pro-globalization economists like Jagdish Bhagwati, and some writers in publications like The Economist, spoke out in favor of a limited role for capital controls. However, even as many developing world economies lost faith in the free market consensus, it remained strong among Western nations.