This book contains the revised and extended versions of selected papers from the 12th International Conference on Agents and Artificial Intelligence, ICAART 2020, held in Valletta, Malta, in February 2020. Overall, 45 full papers, 74 short papers, and 56 poster papers were carefully reviewed and selected from 276 initial submissions. 23 of the 45 full papers were selected to be included in this volume. These papers deal with topics such as agents and artificial intelligence.