Bringing together twenty Italian and international scholars, this Companion provides the most comprehensive overview to date of the Italian Reformation and its historiography. Moving beyond older narratives of a “failed Reformation,” it explores the distinctive features of religious dissent in sixteenth-century Italy, its protagonists, ideas, networks, and interactions with the wider European world. Covering themes ranging from spiritual movements and exile to art, politics, gender, and the Roman Inquisition, the volume both synthesizes four decades of innovative research and points toward new avenues of inquiry, establishing an essential point of reference for future scholarship.