In August 1942, a group of bishops in the French Catholic Church defected from the episcopate’s support for the anti-Semitic Vichy regime to save Jews during the Holocaust. At that time, thousands of Jews were being rounded up by policemen organized by Vichy administrators with the tacit consent of the Church and sent to concentration camps as part of the Nazi plan to exterminate European Jewry. When French bishops deviated from their previous political stance, this was a dramatic change from two years prior when the Assembly of Cardinals and Archbishops had met and decided to formally endorse Vichy’s anti-Semitic policies. “No one more than I recognizes the evil that Jews have done to France,” proclaimed Cardinal Pierre-Marie Gerlier in autumn 1941. Ten months later, he along with four other French bishops, issued a protest that would come to be read from over 400 pulpits throughout France. “The Jews are our brothers. They belong to mankind,” clergy declared. “No Christian dare forget that!” This dissertation examines how French bishops during the Holocaust in France deviated from their support for Vichy to help save Jews despite the high personal and institutional costs associated with defection. The Catholic Church was a primary source of political and moral guidance during the Holocaust in France. When French bishops endorsed the Vichy regime, they legitimized discrimination by officially supporting anti-Semitic policies. Later, their deviation from this stance and protest of the French state’s persecution of Jews de-legitimized the Vichy regime and mobilized Catholics on behalf of European Jewry. In the end, French civilians saved the second-largest number of Jews in any occupied country during the Holocaust. I analyze newly available historical sources written in French, English, and Hebrew and collected from fifteen archives in France, the United States, and Israel, to explain how individuals and institutions trade the benefits of stability for the risky behavior associated with collective action in violent contexts.