The Introduction addresses the difficulty of providing a precise definition of the genre of books of advice to princes. Particular books have been selected because they were owned by or produced for an English prince during the period extending from the early fifteenth century to 1485. The first four chapters are devoted to a consideration of authoritative works which were translated from Latin or French and to treatises which were specially composed for a prince. The anonymous Tractatus de Regimine Principuin, Ashby's Active Policy of a Prince and the Fastolf/Worcester production, the Boke of Noblesse are largely original works. Their contents are subjected to a more extended analysis and the view of good princely government they contain is discussed. Chapter 5 starts with an account of the political writings of Sir John Fortescue, particular attention is paid to the De Laudibus Legum Anglie and the Governance of England as it is claimed that they belong to the genre of books of advice. An attempt is then made from a close examination of the internal evidence to assign a date to the Governance and extend understanding of the circumstances of its composition. The final chapter reviews contemporary documents for indications that the ideas and assumptions of the rulers and their followers were influenced by the precepts contained in books of advice. It is suggested that princely regard for these works can be demonstrated and that their impact must he seen in the wider context of the ethical values to which contemporary society subscribed. There are, however, indications in some popular manifestos, parliamentary petitions and the works of Fortescue of a growing unease at placing undue reliance on the personal qualities of a prince. The need to establish constitutional devices which would negate the weakness of a particular king was increasingly recognised.