In modern times, various Jewish groups have argued whether Jewishness is a function of ethnicity, of nationality, of religion, or of all three. These fundamental conceptions were already in place in antiquity. The peculiar combination of ethnicity, nationality, and religion that would characterize Jewishness through the centuries first took shape in the second century B.C.E. This brilliantly argued, accessible book unravels one of the most complex issues of late antiquity by showing how these elements were understood and applied in the construction of Jewish identity—by Jews, by gentiles, and by the state.

Beginning with the intriguing case of Herod the Great's Jewishness, Cohen moves on to discuss what made or did not make Jewish identity during the period, the question of conversion, the prohibition of intermarriage, matrilineal descent, and the place of the convert in the Jewish and non-Jewish worlds. His superb study is unique in that it draws on a wide range of sources: Jewish literature written in Greek, classical sources, and rabbinic texts, both ancient and medieval. It also features a detailed discussion of many of the central rabbinic texts dealing with conversion to Judaism.