This volume presents the papers contributed to ?EON 2008, the 10th Int- national Conference on Deontic Logic in Computer Science, held in Fiesole (Florence), July 7-9, 2010. This biennial conference series is designed to p- mote international cooperation amongst scholars who are interested in deontic logic and its use in computer science. The scope of the conference is interd- ciplinary, it covers formal-logical studies of normative concepts and normative systems and their links with computer science, arti?cial intelligence, philosophy, organization theory, and law. This edition of ?EON invited submission on the following general themes: the logical study of normative reasoning, including formal systems of deontic logic, defeasible normative reasoning, the logic of action, and other related - eas of logic, the formal analysis of normative concepts and normative systems, the formal representation of legal knowledge, the formal speci?cation of aspects of norm-governed multi-agent systems and autonomous agents, including (but not limited to) the representation of rights, authorization, delegation, power, responsibility and liability, the formal speci?cation of normative systems for the managementofbureaucraticprocessesinpublic orprivateadministration,app- cations of normative logic to the speci? cation of database integrity constraints, normative aspects of protocols for communication, negotiation and multi-agent decision making.In particular,submissions weresolicited addressingapplication of deontic notions for modelling legal systems.