 This article describes the most important sources of medieval political ideas and the work of some of the most interesting writers. The main sources were the Bible, the Fathers of the Church, the textbooks of canon and civil law, and the works of Aristotle, especially the Politics. Sections 2 and 3 will outline what medieval political thought took from the Bible and the Fathers. Sections 4 and 5 will sketch the ideas of political thinkers of the pre-scholastic period, including Augustine. Sections 6 and 7 will sketch the sources that became influential during the twelfth and thirteenth centuries, namely Aristotle and the law textbooks. Section 8 will outline one of the main issues of medieval political thought from the thirteenth century onwards, namely the political power of the pope. Section 9 will outline the work of a major thirteenth century writer, Thomas Aquinas. Sections 10–14 will be concerned with writers on political philosophy during the 14th and 15th centuries, including Marsilius of Padua and William of Ockham.