The historical studies presented here examine four ideologies― Leninism, Trotskyism, anarchism, and anti-imperialism― still with us, however different and diffuse in form. They are a contribution to the worldwide Marx renaissance of recent decades which has helped clear away the legacies of the Second, Third and Fourth Internationals, not to mention of the ‘real existing socialism’ of the Soviet Union and its bastard progeny. These revolutionary predecessors did not fail because ‘they had the wrong ideas’; in contrast to today, they were merely embedded in an earlier dynamic where capitalism, globally, was not yet fully dominant. The cases of Russia, Turkey, Spain and Bolivia allow us to measure the distance between their epoch and our own, and to clear away their problematic legacies.