This book constitutes the refereed proceedings of the 12th International Workshop on Cooperative Information Agents, CIA 2008, held in Prague, Czech Republik, in September 2008. The book contains 5 invited papers and 19 revised full papers which were carefully reviewed and selected from 38 submissions. The papers are organized in topical sections on Trust, Applications, Coordination and Communications, and Negotiation.

Invited Contributions.- Enabling Networked Knowledge.- Coordination and Agreement in Multi-Agent Systems.- Agents and Databases: A Symbiosis?.- Agents and Semantic Services: A Critical Review.- Agent-Supported Planning in Distributed Command and Control Environments.- Trust.- Towards Trust-Based Acquisition of Unverifiable Information.- Modeling Dynamics of Relative Trust of Competitive Information Agents.- A Formal Approach to Aggregated Belief Formation.- Applications.- Software Engineering for Service-Oriented MAS.- A Service-Oriented MultiAgent Architecture for Cognitive Surveillance.- Trust-Based Classifier Combination for Network Anomaly Detection.- A Distributed Generative CSP Framework for Multi-site Product Configuration.- MobiSoft: Networked Personal Assistants for Mobile Users in Everyday Life.- A Web-Based Virtual Machine for Developing Computational Societies.- Using the Wizard of Oz Method to Train Persuasive Agents.- ASBO: Argumentation System Based on Ontologies.- Coordination and Communication.- Controling Contract Net Protocol by Local Observation for Large-Scale Multi-Agent Systems.- Filter Allocation Using Iterative ECNP.- On the Use of Symbolic Data Analysis to Model Communication Environments.- Commitment-Based Multiagent Decision Making.- Negotiation.- Towards an Open Negotiation Architecture for Heterogeneous Agents.- Incrementally Refined Acquaintance Model for Consortia Composition.- Towards a Monitoring Framework for Agent-Based Contract Systems.- Collaborative Load-Balancing in Storage Networks Using Agent Negotiation.