Horkheimer and Adorno, the central figures of the Frankfurt School, returned to Germany after the war and re-established the institute at Frankfurt University. Adorno died in 1969, Horkheimer in 1973. In their last years their views underwent considerable change, partly as the result of a collision with the New Left whom they regarded (in contrast to Marcuse) as "left-wing fascists". Horkheimer, who had always tended towards pessimism, became more conservative with age. Adorno, while not a puritan, never quite overcame the shock caused by some female students who, appearing bare-breasted, tried to kiss him and thus break up his classes. Flashing was not part of the Dialectic of Enlightenment as he understood it.

The tradition of critical theory lingered on in the United States, Germany and a few other places but mainly in the field of cultural studies. In the United Kingdom an offshoot has appeared in the form of a journal, Critical Terrorism Studies, published at the Centre for the Study of Radicalisation and Contemporary Political Violence at Aberystwyth University. A book entitled Rethinking the Roots of Terrorism (2006) from the University of St Andrews claims to base itself on the critical theory of the Frankfurt School. But its real concern is with the evil doings of anti-terrorism rather than the theory and practice of terrorism. Providence and critical theory have moved in strange and mysterious ways and the end may not yet be in sight.