This article explores communism – including its pre-history and aftermath – as a generational history. The structure is diachronic and largely biographical. Attention is paid to the roles of milieu, the Second World War, generational cleavages and a Hegelian sense of time. Nineteen sixty-eight is a turning point, the moment when Marxism as belief was decoupled from communism as practice. The arrival of Soviet tanks in Prague meant a certain kind of end of European Marxism. It also meant the coming of age of a new generation: those born in the post-war years who were to play a large role in the opposition. The anti-communist opposition was organically connected to Marxism itself: the generation(s) of dissidents active in the 1970s and 1980s should be understood as a further chapter in the generational history of communism. Nineteen eight-nine was another moment of sharp generational rupture. The new post-communist generation, Havel's great hope, possessed the virtue of openness. Openness, however, proved a double-edged sword: as eastern Europe opened to the West, it also opened a Pandora's box. Perhaps today the most poignant generational question brought about by 1989 is not who has the right to claim authorship of the revolution, but rather who was old enough to be held responsible for the choices they made under the communist regime. There remains a division between those who have to account for their actions, and those who do not, between those who proved themselves opportunists, or cowards or heroes – and those who have clean hands by virtue of not having been tested.