This book constitutes the thoroughly refereed post-conference proceedings of the 11th International Workshops on Coordination, Organizations, Institutions and Norms in Agent Systems, COIN 2015. The workshops were co-located with AAMAS 2015, held in Istanbul, Turkey, in May 2015, and with IJCAI 2015, held in Buenos Aires, Argentina, in July 2015.

Reasoning with Group Norms in Software Agent Organizations.- A Cognitive Framing for Norm Change.- Representative Agents and the Cold Start Problem in Contract Negotiation.- Simulating Normative Behavior in Multi-Agent Environments Using Monitoring Artefacts.- Exploring the Effectiveness of Agent Organizations.- SIMPLE: a Language for the Specifiation of Protocols, Similar to Natural Language.- Mind as a Service: Building Socially Intelligent Agents.- COIR: Verifying Normative Specifications of Complex Systems.- The Role of Knowledge Keepers in an Artificial Primitive Human Society: an Agent-Based Approach.- Modeling and Detecting Norm Conflicts in Regulated Organizations.- Revising Institutions Governed by Institutions for Compliant Regulations.- Reinforcement Learning of Normative Monitoring Intensities.- Communication in Human-Agent Teams for Tasks with Joint Action.- Manipulating Conventions in a Particle-based Topology.- Formation of Association Structures Based on Reciprocityand Their Performance in Allocation Problems.- Towards Team Formation via Automated Planning.- Interest-based Negotiation for Policy-regulated Asset Sharing.- An Empirical Evaluation of the Huginn Constrained Norm-aware BDI Reasoned.- Implementation of Normative Practical Reasoning with Durative Actions.- Multi-agent Team Formation for Design Problems.- Security and Robustness for Collaborative Monitors.- An Interactive, Generative Punch and Judy Show Using Institutions, ASP and Emotional Agents.- Quantified Degrees of Group Responsibility.