This essay examines the Third World volunteer movement that developed within the Catholic world in the late 1950s and the following decade. Groups and associations selected applications from dozens of young people, trained aspiring lay missionaries, and sent them to religious missions in Africa and Latin America to work as volunteers in the fields of education, health care, and construction. The essay reconstructs the activities of the organisations, but also the way in which aid to "poor countries" was conceived, in terms of the ethical values it invoked and the effects it hoped to produce. The history of Italian cooperation is placed in an international context, going beyond the measurement of Italy's backwardness in the field of aid policy, to capture some elements of specificity through the categories of analysis provided by the historiographic debate on contemporary humanitarianism.