This is the first volume of a two-volume edition of the Chronicle by Symeon Logothetes (10^th cent.), one of the main sources for Middle Byzantine history. The text is presented here in a critical edition for the first time. In the introduction, all manuscripts are described, and the relationships between them analysed. Wahlgren’s findings differ in significant points from the (partial) analyses of earlier researchers. The edition has to be based mainly on the 11^th cent. manuscript because the Slav versions of the Chronicle are of only little value for the reconstruction of the original text. Navigation through the volume is facilitated by comprehensive indexes. A projected second volume will provide an edition of versions and continuations of the Chronicle.