The papers in this volume are the refereed technical papers presented at AI-2005, the Twenty-fifth SGAI International Conference on Innovative Techniques and Applications of Artificial Intelligence, held in Cambridge in December 2005. The papers in this volume present new and innovative developments in the field, divided into sections on Information Learning, Integration and Management, AI and the World Wide Web, Networks and Biologically Motivated AI, Multi-Agent Systems, Case-Based Reasoning, Knowledge Discovery in Data and Reasoning and Decision Making. This is the twenty-second volume in the Research and Development series. The series is essential reading for those who wish to keep up to date with developments in this important field. The Application Stream papers are published as a companion volume under the title Applications and Innovations in Intelligent Systems XIII.