How did purity evolve into the one most significant religious category during the Second Temple period? What was the role of purity discourse in the reformation of Jewish society and religion in Late Antiquity? The concern for purity shaped Second Temple Judaism, and its significance expanded far beyond the limited realm of the Temple. The fear of impurity shaped daily conduct, stood at the heart of ideological discourse and set the contours of Jewish society. The question how to ensure ritual and moral purity was of cosmic dimensions, and therefore determined the dividing lines between the main parties of Jewish society in Palestine. The Qumran sect developed the notion of the defiling sin, and Jesus was viewed by his followers as the ultimate purifier. Against these alternatives, this book offers a comprehensive analysis of the purity policy in the teachings of the dominant Pharisees. Early rabbinic traditions alongside anti-pharisaic sources uncover a controversial policy focused on the body and not on the purity of the Temple. They provided purification to wider social circles, while preserving its role in maintaining their own status. The book further demonstrates the fundamental change of religious life and social practices from the Second Temple period through the rise of the rabbinic movement, which offered a new version of ritual purity and community. A close analysis of the halakhic traditions in rabbinic literature reveals the gradual disintegration of the ancient religious culture and the emergence of the rabbinic culture within new social contexts.