This is the first text edition of the catechism of Cyril of Jerusalem in the Christian Palestinian Aramaic version (ca 5th-7th centuries AD). About a third of the volume comprises previously unpublished text material. The real importance of this Aramaic version is that it is based on a translation from an earlier Greek version now lost. For comparison, the Aramaic part has been juxtaposed with the Greek text of the critical edition of 1848. A glossary of the Aramaic words has been included.