De incarnatione by Theodore of Mopsuestia (350–428), written at the beginning of the Christological controversies, was repeatedly at the centre of debate until Theodore’s condemnation in 553. This study on the transmission of the surviving fragments of this work offers insights into the course the controversies and clarifies the question of the text’s reliability. For the first time both the extent and the order of the fragments are considered critically. The critical Greek and Latin text, forming the basis of the new presentation of Theodore’s Christology, is provided with a translation.