Clavis Patrum Graecorum (CPG) has provided an invaluable service to scholars for many years. However, its last supplement was printed more than 20 years ago and, thus, this instrument is out-of-date. Clavis Origenis therefore intends to fill this gap by providing on-line and up-to-date information to scholars regarding Origen’s texts. Clavis Origenis focuses on critical editions, textual tradition, critical problems of the texts, older versions of the texts, the relations between texts and fragments or Greek texts and Latin translations, modern translations, etc. It does not tackle the interpretation of Origen’s works but instead only focuses on their texts. Every entry of Clavis Origenis covers a group of works. The grouping follows the order of biblical books and it does not coincide with the numbering of CPG.