This book constitutes the proceedings of the 12th German Conference on Multiagent System Technologies, MATES 2014, held in Stuttgart, Germany, in September 2014. The 9 full papers and 7 short papers included in this volume were carefully reviewed and selected from 31 submissions.

Social Choice Theory as a Foundation for Multiagent Systems.- A Boolean Game Based Modeling of Socio-Technical Systems.- Evaluating Strategies for Penny Auctions Using Multi-Agent Systems.- Robustness Analysis of Negotiation Strategies through Multiagent Learning in Repeated Negotiation Games.- Using Multi-attribute Combinatorial Auctions for Resource Allocation.- A Negotiation-Based Genetic Framework for Multi-Agent Credit Assignment.- Agent-Based Concepts for Manufacturing Automation.- Orchestrating the Sequential Execution of Tasks by a Heterogeneous Set of Asynchronous Mobile Agents.- A Conceptual Framework of a Decision Support System for Operational Dispatching of Agricultural Bulk Goods – An Agent-Based Approach.- Planning with Numeric Key Performance Indicators over Dynamic Organizations of Intelligent Agents.- Employing Automatic Temporal Abstractions to Accelerate Utile Suffix Memory Algorithm.- The Effects of Variation on Solving a Combinatorial Optimization Problem in Collaborative Multi-Agent Systems.- Complexity Measurement of Multi-Agent Systems.- Extensible Java EE-based Agent Framework in Clustered Environments.- Programming BDI Agents with Pure Java.- AGADE: How Individual Guidance Leads to Group Behaviour and How This Can Be Simulated.- A Tree-Based Context Model to Optimize Multiagent Simulation.- Agent-Based Modeling and Simulation of the Emotional and Behavioral Dynamics of Human Civilians during Emergency Situations.