Western European Liberation Theology is the first comprehensive survey of the development of a distinct, progressive variant of Catholicism in twentieth-century Western Europe. This Left Catholicism served to lay the basis for the subsequent events and evolutions associated with Vatican II. Initially emerging within the boundaries of Catholic Action, fuelled by the growing power and self-confidence of the Catholic laity, a series of challenges to received wisdom and an array of novel experiments were launched in various corners of Western Europe. The moment of liberation from Nazi occupation and world war in 1944/45 turned out to be the highpoint of these optimistic paradigm shifts. Concentrating on interrelated developments in theology, Catholic politics and apostolic social action, Gerd-Rainer Horn integrates evidence from Italian, French and Belgian national contexts. Drawing on his research in over twenty archives between Leuven and Rome, he highlights the role of organisations, social movements, and intellectual trends. The pivotal contributions of key individuals are assessed, from theologians such as Jacques Maritain and Emmanuel Mounier, to the millenarian activist priests, Don Zeno Saltini and Don Primo Mazzolari. In conclusion Horn suggests that first-wave Western European Left Catholicism served as an inspiration - and constituted a prototype - for subsequent Third World Liberation Theology.