The thirteenth volume of the edition of pope Innocent III’s chancery-registers is containing 207 letters addressed to recipients all over Europe and in the Middle East. Many of the letters are concerned with the church organisation of the Latin Empire, especially after the Latin take-over in Greece. Others are dealing with political and ecclesiastical issues from Southern Italy to Scandinavia, matrimonial matters and property questions, privileges and confirmations of rights and possessions of bishoprics and monasteries, matters concerning the episcopate and litigation within the Church, such as contested elections or disciplinary problems, and a variety of decisions offering insights in major and minor problems of the church and the people around 1200. The register of Innocent’s thirteenth year of pontificate is the first of four volumes transmitted not as original but as a copy written at the Curia in mid-14th century and as print published by the French scholar Bosquet in the 17th century. The volume is offering the critical edition of the texts, ample historical comments, identifications of textual parallels and quotations from the Bible, Canon and Roman law, theological, liturgical and classical texts, and the insertion of the letters in decretal collections. In the introduction, the manuscript and the editorial principles are described, and several indices help to access the contents.