These ten essays by John Van Engen situate religion in the history of medieval Western Europe: as an unavoidable presence in everyday life, as a conceptual framework for social and political life, as a force integral to its historical dynamics. Four of the essays are bibliographical and retrospective in nature, reviewing the field broadly, but also pointing toward a more dialectical approach to understanding the interaction of religion and society in the European middle ages. Other studies deal with large topics usually subsumed under the abstract term 'Christianization'. They grapple with learned sources as well as those associated with 'popular' religion, and show what can be gained from an imaginative use of all that lawyers and theologians said about religion in their society. The essays, finally, look for the quality and dynamic of change, even inventiveness, released by religious action and conviction in medieval European society.