This study is the first extensive scholarly treatise on the Chapter of St. Peter’s in the Vatican since the 18th century. It analyzes the statutes of the Chapter, its prosopographical composition as well as the relationship to the popes. The appendix contains concise biographies of the canons and an edition of the two oldest interest registers of the Chapter of St. Peter’s. A comparison with the chapters of St. Giovanni in Laterano and St. Maria Maggiore reveals the outstanding position of the Chapter of St. Peter’s with respect to the structure of the city and to the Curia.