[With the Collaboration of Adam Kamesar] Philo of Alexandria has left an extensive body of works that have influenced a vast range of subsequent biblical, historical, philosophical, and theological studies. But, like the works of other writers of antiquity, the preservation of Philo's works has been far from straightforward. The majority of Philo's works have come down to us in the original Greek. Some, however, have been preserved in Armenian translations dating from the sixth century. Much more limited in scope is a Latin version, which retains some importance, however. The process of textual transmission, both in Greek and in translation, has to a certain degree obscured whatever principles of organization may have been established by Philo himself or by early guardians of his corpus. However, through the losses and the corruption, scholars have been able to identify wider structures and superior manuscripts. What is presented here is an overview of the current consensus regarding Philo's works, and an indication of some of the problems involved in the reconstruction of what Philo originally wrote.