This book constitutes the refereed proceedings of the 12th International Conference of the Italian Association for Artificial Intelligence, AI*IA 2011, held in Palermo, Italy, in September 2011. The 31 revised full papers presented together with 3 invited talks and 13 posters were carefully reviewed and selected from 58 submissions. The papers are organized in topical sections on machine learning; distributed AI: robotics and MAS; theoretical issues: knowledge representation and reasoning; planning, cognitive modeling; natural language processing; and AI applications.