This book is the first systematic enquiry into the ways Philo saw himself as a Jew and perceived of Jewish culture in the multi-ethnic environment of first century Alexandria. Applying the theories of ethnicity and culture developed by Frederik Barth and Clifford Geertz, the book gives emphasis to the nature and dynamics of social constructs which shaped Philo's discourse and religion. Particular attention is in this context paid to his construction of others. Furthermore, Rome is for the first time taken into account as a political, cultural and religious factor which exercised an all-encompassing influence. Philo's writings are thus interpreted with a view to the question how he negotiated not two, but three main traditions, namely the Jewish, the Roman and the Greek, and how his positions integrated him into the contemporary Roman discourse. Philo's views on these matters have important implications beyond his own figure and the Jewish community. They are crucial for a better understanding of the Hellenistic world which was in the first century to a large extent characterized by the encounter between the Greek East and the Roman West. Philo's construction of Jewish identity and culture is moreover indispensable for a proper appreciation of early Christian writers who lived in the same world and confronted very similar issues.