The Protestant Reformation is one of the defining events of the last millennium. Nearly 500 years after the Reformation, its causes and consequences have seen a renewed interest in the social sciences. Research in economics, sociology, and political science increasingly uses detailed individual-level, city-level, and regional-level data to identify drivers of the adoption of the Reformation, its diffusion pattern, and its socioeconomic consequences. We take stock of this research, pointing out what we know and what we do not know and suggesting the most promising areas for future research.