This study analyzes the impact of the Czechoslovak crisis of 1968-1969 on the two major communist parties in the West: the Italian and French ones. Discusses the central strategic and ideological tensions which these parties needed to deal with: domestic belonging versus allegiance to the world communist movement, doctrinal orthodoxy in a context of rapid societal changes, and the question of revolution and reform. These key problems were situated in different contexts: the crisis in the "world communist movement" after 1956 and the Sino-Soviet rift, socio-economic modernization and political radicalization in Western Europe, and the shift from Cold War to early d tente on the European continent. The research for this work is based on the study of a large collection of recently released primary sources, particularly, the internal records of various communist parties in Europe.