In late July 1263 a public disputation was convened by King James I of Aragon, pitting Friar Paul Christian against the distinguished rabbi of Gerona, Moses ben Nahman. Organized by leading figures in the Dominican Order to give Friar Paul an opportunity to test his innovative missionizing argumentation against a worthy opponent, the spectacle in Barcelona was colorful, impressive, surely somewhat frightening to the Jews, and ultimately indecisive. Both sides claimed victory, and their documented claims have given rise to substantial disagreement among historians over the tone and outcome of this important event. Robert Chazan's masterly analysis reconstructs the Barcelona disputation from the conflicting Christian and Jewish sources and sets it in its broad historical context, with particular attention to the post-disputation maneuvers on both sides. His richly detailed account focuses on Rabbi ben Nahman's eloquent efforts to reassure his fellow Jews in the face of new missionizing pressures.