This book is the first English commentary on Philo’s In Flaccum since the publication of Box in 1939. The work contains an introduction in which matters of genre, historical background, the textual evidence etc. are discussed. This is followed by a new English translation of the Greek text. The main part of the book is a detailed philological and historical commentary on Philo’s text. Since In Flaccum is our only source for the anti-Jewish pogrom in Alexandria in the year 38 CE, it is of the utmost significance for the study of the origins and early history of antisemitism. The book is of interests for scholars of Judaism, Ancient History, Biblical Studies, Classical Literature, and History of Religions.