Invited Contributions -- On the Convergence of Structured Search, Information Retrieval and Trust Management in Distributed Systems -- Semantic Methods for P2P Query Routing -- Programming Cognitive Agents -- Workflows and Group Interaction -- Enacting the Distributed Business Workflows Using BPEL4WS on the Multi-agent Platform -- BSCA-P: Privacy Preserving Coalition Formation -- Towards Service Coalitions: Coordinating the Commitments in a Workflow -- Reasoning about Utility -- Modeling Minority Games with BDI Agents – A Case Study -- A Goal Deliberation Strategy for BDI Agent Systems -- Estimating Utility-Functions for Negotiating Agents: Using Conjoint Analysis as an Alternative Approach to Expected Utility Measurement -- The Dynamics of Knowledge -- Reconciling Agent Ontologies for Web Service Applications -- An Agent-Based Knowledge Acquisition Platform -- An Agent Architecture for Ensuring Quality of Service by Dynamic Capability Certification -- Engineering a Multi Agent Platform with Dynamic Semantic Service Discovery and Invocation Capability -- Methodology and Simulation -- Towards a Formal Methodology for Designing Multi-agent Applications -- LEADSTO: A Language and Environment for Analysis of Dynamics by SimulaTiOn -- Agent Tools and Agent Education -- Towards a Distributed Tool Platform Based on Mobile Agents -- The Distributed Weighing Problem: A Lesson in Cooperation Without Communication -- Short Papers -- An Adaptive Reputation Model for VOs -- Realising Reusable Agent Behaviours with ALPHA -- Multi-agent System Specification Using TCOZ -- ABACO, Coordination of Autonomous Entities -- Agent-Based Simulation for Testing Control Software of High Bay Warehouses -- Posters -- Collaborative Agent-Based Knowledge Support for Empirical and Knowledge-Intense Processes -- Experiments in Neo-computation Based on Emergent Programming -- A Framework Based on Multi-agent Systems for Information Retrieval Through Mobile Devices -- CASCOM: Context-Aware Service Co-ordination in Mobile P2P Environments.After two successful MATES conferences in Erfurt 2003 and 2004, the 3rd G- man conference on Multi-agent System Technologies (MATES 2005) took place in Koblenz, Germany, in September 2005, and was co-located with the 28th German Conference on Arti?cial Intelligence (KI 2005). Building onotheragent-relatedeventsinGermanyinthepast,andorganized by the GI German Special Interest Group on Distributed Arti?cial Intelligence, the MATES conference series aims at promoting the theory and applications of agentsandmultiagentsystems.Incorporatingthe9thInternationalWorkshopon Cooperative Information Agents (CIA 2005), the topics of interest for MATES 2005 also covered the ?elds of intelligent information agents and systems for the Internet and the (Semantic) Web. As in recent years, MATES 2005 provided a distinguished, lively and int- disciplinary forum for researchers, users, and developers of agent technology, to present and discuss the latest advances of research and development in the area of autonomous agents and multiagent systems. Accordingly, the topics of MATES 2005 covered the whole range from the theory to applications of age- and multiagent technology. The technical program included a total of 24 sci- ti?c talks, and demonstrations of selected running agent systems, and both the MATES 2005 Best Paper and the CIA 2005 System Innovation awards.