Political life in the advanced industrial democracies since the Second World War has been characterized by periods of mass mobilization and protest followed by years of relative quiescence and institutional dominance. The individual phases have prompted extensive reflection. Far less attention, however, has been devoted to how developments in one phase might influence the subsequent one. Using data from a 1979 survey of activists of the Italian Communist Party, this article examines how the cycle of protest which swept Italy in the late-1960s and early-1970s was reflected in the distribution of attitudes towards dissent within the different generations of party activists. Our findings clearly suggest that participation in social movements had independent effects on the presence of particular tolerance attitudes and that phases of mobilization affect the distribution of politically salient attitudes among party activists during a subsequent phase of institutionalization. This, in turn, has possible implications for processes of change in the Italian political system.