In contrast to the experience of many other countries, notably Spain and France, in Portugal, municipal financial and accounting ledgers have been long overlooked as important and precise repositories of data for the study of medieval urban and economic history. Part of the reason for this has been a general paucity of sources which, however, is far from true in the case of Loule, a small town in possession of a collection of accounting records representing the oldest and second largest such series in the country. Through an examination of this exceptional reserve, this article seeks to contribute to a deeper understanding of the process of compilation and management of books of accounts in medieval Portuguese small and medium-size towns. Subjects probed include a contemplation of the municipal officials involved in town finances, the process of preparation, organisation and control of accounting ledgers, and the role of auditors and their procedures. Concluding remarks reflect on the conservation of accounting ledgers and implications for the future analysis of other book-keeping records.