This study examines the rise, spread, and decline of Protestant reform movements in Polish society, arguing that social and economic forces rather than purely religious motives drove their development. It outlines institutional and cultural background, analyzes social causes and the economic effects of the church’s wealth on the nobility, and treats the noble‑clergy conflict as fundamentally economic. The author links rapid early growth to short‑term material incentives and attributes the later collapse to shifting economic structures, presenting evidence organized into chapters on development, social causes, ecclesiastical wealth, economic conflict, and supporting appendices and bibliography.