Source: http://www.catholicinsight.com/online/features/article_882.shtml
Basically, the Frankfurt School’s task was, as swiftly as possible, to undermine the Judaeo-Christian legacy. To do this they called for the most negative destructive criticism possible of every sphere of life which would be designed to de-stabilize society and bring down what they saw as the ‘oppressive’ order. Their policies, they hoped, would spread like a virus—‘continuing the work of the Western Marxists by other means’.
Carl Grünberg, the Institute’s director from 1923-1929, was an avowed Marxist, although the Institute did not have any official party affiliations. But in 1930 Max Horkheimer assumed control and he believed that Marx’s theory should be the basis of the Institute’s research. When Hitler came to power, the Institut was closed and its members, by various routes, fled to the United States and migrated to major US universities—Columbia, Princeton, Brandeis, and California at Berkeley.