We have found a short article on massline.org which offers a brief summary of the Frankfurt School
The Frankfurt School was centered around what was officially known as the Institute for Social Research, which was founded and affiliated with the University of Frankfurt in 1923 under the direction of Carl Grünberg.
During the Nazi era it was forced to relocate to New York, but returned home in 1949.
Among its leading lights were Max Horkheimer, who was the Director from 1931 to 1958, Walter Benjamin, Theodor Adorno and Herbert Marcuse, who had a considerable influence on some of the leaders of the New Left in the U.S. during the 1960s.
Its leading later representative is Jürgen Habermas. The programme of the school was supposedly to construct a “critical theory” of Marxism, which they characteristically tried to do in academia and in a way completely divorced from the mass revolutionary movement!
In other words, the Frankfurt School in actual practice has been primarily a loose association of intellectual revisionists who were influenced by Marxism to some degree, but who sought to reconstruct it along the much more idealist and bourgeois lines which were acceptable to them.
They found a great deal to criticize in Marx and Engels, and even more to criticize in Lenin. Later they added Mao to their list of Marxist-Leninists they didn’t much care for.
One of their most consistent themes was to oppose materialism. They used this sneaky approach: they identified materialism and its defense with Stalin and his USSR in order to discredit it with their target audience.
As much as possible they tried to ignore or deny the plain fact that all the great developers of the science of revolutionary Marxism have been staunch and extremely consistent materialists.
In particular they tried to distort Marx’s early writings to make him out to be some sort of Hegelian idealist!
Their second sneaky trick was to absurdly claim that dialectical materialism as it has been understood within Marxism-Leninism was actually a form of “positivism”!
And in general the Frankfurt School has focused almost entirely on the superstructure of society, with a determination to put an idealist slant on their interpretation of it.
Like most idealists, they found Kant attractive when it comes to epistemology.
They were also enthusiastic about psychoanalysis, despite the fact that it is mostly a pseudoscience. The psychoanalyst Erich Fromm was one of those associated with the Frankfurt School.
The Frankfurt School rejected orthodox Marxism as a “dogma”. It seems only fair, therefore, that we revolutionary Marxists should reject the Frankfurt School as silly idealist revisionism!