This volume constitutes the first attempt to analyse the phenomenon of Western European Left Catholicism from a comparative and transnational perspective. Decisively shaped by the turbulent atmosphere of war, occupation and resistance, the years 1943-1955 gave rise to a most unusual flowering of progressive initiatives in Catholic politics, theology and apostolic missions. Though suffering severe setbacks in the deep freeze of Cold War politics, mid-century Western European Left Catholicism was not without influence in the subsequent emergence of Latin American Liberation Theology and the deliberations of Vatican II.