This Book Constitutes The Refereed Proceedings Of The 12th Portuguese Conference On Artificial Intelligence, Epia 2005, Held In Covilhã, Portugal In December 2005 As Nine Integrated Workshops. The 58 Revised Full Papers Presented Were Carefully Reviewed And Selected From A Total Of 167 Submissions. In Accordance With The Nine Constituting Workshops, The Papers Are Organized In Topical Sections On General Artificial Intelligence (gaiw 2005), Affective Computing (ac 2005), Artificial Life And Evolutionary Algorithms (alea 2005), Building And Applying Ontologies For The Semantic Web (baosw 2005), Computational Methods In Bioinformatics (cmb 2005), Extracting Knowledge From Databases And Warehouses (ekdb&w 2005), Intelligent Robotics (irobot 2005), Multi-agent Systems: Theory And Applications (masta 2005), And Text Mining And Applications (tema 2005).