The Observant Movement was a widespread effort to reform religious life across Europe. It took root around 1400, and for a century and more thereafter it inspired or shaped much that became central to European religion and culture. The Observants produced many of the leading religious figures of the later Middle Ages—Catherine of Siena, Bernardino of Siena and Savonarola in Italy, Francisco Jiménez de Cisneros in Spain, and in Germany Martin Luther himself. This volume provides scholars with a current, synthetic introduction to the Observant Movement. Its essays also seek collectively to expand the horizons of our study of Observant reform, and to open new avenues for future scholarship.