In the twentieth century, Catholics have been enthusiastic supporters of the dictatorships of Franco and Salazar, victims of Nazism in Germany, and advocates of Christian Democracy in post-war Europe. What unites these experiences? Focusing on the years between the end of the First World War and the Second Vatican Council in the 1960s, a group of expert historians tackle this issue on a country-by-country basis, investigating how Catholicism represented not only a religious, but also a major political and social force in European politics.