group of researchers associated with the Institute for Social Research in Frankfurt am Main, Ger., who applied Marxism to a radical interdisciplinary social theory. The Institute for Social Research (Institut für Sozialforschung) was founded by Carl Grünberg in 1923 as an adjunct of the University of Frankfurt; it was the first Marxist-oriented research centre affiliated with a major German university. Max Horkheimer took over as director in 1930 and recruited many talented theorists, including T.W. Adorno, Erich Fromm, Herbert Marcuse, and Walter Benjamin.

The members of the Frankfurt School tried to develop a theory of society that was based on Marxism and Hegelian philosophy but which also utilized the insights of psychoanalysis, sociology, existential philosophy, and other disciplines. They used basic Marxist concepts to analyze the social relations within capitalist economic systems. This approach, which became known as “critical theory,” yielded influential critiques of large corporations and monopolies, the role of technology, the industrialization of culture, and the decline of the individual within capitalist society. Fascism and authoritarianism were also prominent subjects of study. Much of this research was published in the institute's journal, Zeitschrift für Sozialforschung (1932–41; “Journal for Social Research”).

Most of the institute's scholars were forced to leave Germany after Adolf Hitler's accession to power (1933), and many found refuge in the United States. The Institute for Social Research thus became affiliated with Columbia University until 1949, when it returned to Frankfurt. In the 1950s the critical theorists of the Frankfurt School diverged in several intellectual directions. Most of them disavowed orthodox Marxism, though they remained deeply critical of capitalism. Marcuse's critique of what he perceived as capitalism's increasing control of all aspects of social life enjoyed unexpected influence in the 1960s among the younger generation. Jürgen Habermas emerged as the most prominent member of the Frankfurt School in the postwar decades, however. He tried to open critical theory to developments in analytic philosophy and linguistic analysis, structuralism, and hermeneutics.