This chapter studies how literate Jewish farmers abandoned farming and became small, urban populations of skilled craftsmen, shopkeepers, traders, money changers, moneylenders, scholars, and physicians. The literacy of the Jewish people, coupled with a set of contract-enforcement institutions developed during the five centuries after the destruction of the Second Temple, gave the Jews a comparative advantage in occupations such as crafts, trade, and moneylending—occupations that benefited from literacy, contract-enforcement mechanisms, and networking. Once the Jews were engaged in these occupations, they rarely converted, which is consistent with the fact that the Jewish population grew slightly from the seventh to the twelfth century. Subsequently, the establishment of the Muslim caliphates during the seventh and eighth centuries, and the concomitant vast urbanization and growth of manufacture and trade in the Middle East, acted as a catalyst for the massive transition of the Jews from farming to crafts and trade.