This dissertation is a study of the usury prohibition in rabbinic literature. It focuses on the usury laws in Tannaitic literature, the first formulation of the usury prohibition as a complex and multifaceted judicial norm. I place the Tannaitic usury laws against the backdrop of the economic and cultural norms of the wider world which the Tannaim inhabited. It is a philological, historical, and cultural study, offering a thick description of the economic and social ideology of the rabbis through the prism of one defined area of halakhah.