This volume contains the proceedings of DEON2020/2021, the 15th International Conference on Deontic Logic and Normative Systems. The biennial DEON conferences are designed to promote interdisciplinary cooperation among scholars interested in linking the formal-logical study of normative concepts, normative language and normative systems with computer science, artificial intelligence, linguistics, philosophy, organization theory and law. In addition to these general themes, DEON2020/2021 encouraged a special focus on the topic "Norms in Social Perspective".