This paper presents a historical investigation of usury in the context of the development of credit activities. The definition of usury and the attitudes towards usury changed multiple times over the centuries. We focus on the 12th to the 14th centuries and the changes in the operating, economic, and reporting practices resulting from changes in the economy - from subsistence farming to sophisticated international trading. We analyse the relationship between the Church’s usury prohibitions and the development of trading and credit. As a one-sentence summary of our conclusions, we can claim that during the 14th century, usury was radically condemned in theory, but despite this prohibition, the Church was not able to contain the spread and the development of credit, and merchants made operations charging interest in the substance of the operations while concealing the existence of interest in visible formal terms.
Keywords: Middle Ages, usury, credit practice, church, lender, Italy