 Current research on the identity of Peter of Spain has once again taken up the idea that he must have been a member of the Dominican Order instead of Pope John XXI (D’Ors 1997, 2001, 2003). However, we are still in the dark about the true identity of Peter of Spain. The most recent information we have on this score is that a number of the Dominican candidates recently suggested as the author of the Tractatus can be deleted from the list (Tugwell 1999, 2006). The lack of further information also makes it difficult to establish the dates and specifics of his carreer.