M.A.Bramer University of Portsmouth, UK This volume comprises the refereed application papers presented at AI-2003, the Twenty-third SGAI International Conference on Innovative Techniques and Applications of Artificial Intelligence, held in Cambridge in December 2003. The conference was organised by SGAI, the British Computer Society Specialist Group on Artificial Intelligence. The papers present new and innovative developments in the field, divided into sections on Personalisation, E-Commerce and Resource Management, Hazard Prediction, Fault Diagnosis and Design, Medical and Social Services and Image Recognition, Knowledge Bases and Attribute Selection. This year's prize for the best refereed application paper, which was sponsored by the Department of Trade and Industry, was won by a paper entitled Design-a-Trial: A Rule-Based Decision Support System for Clinical Trial Design, which has no fewer than nine authors: K Nammuni, C Pickering (lnferMed Ltd), S Modgil (University College, London), A Montgomery (lnferMed Ltd), P Hammond (University College, London), IC Wyatt (National Institute for Clinical Excellence), DG Altman (Centre for Statistics in Medicine), R Dunlop (lnferMed Ltd) and H Potts (Kings College, London). This is the eleventh volume in the Applications and Innovations series. The Technical Stream papers are published as a companion volume under the title Research and Development in Intelligent Systems XX. On behalf of the conference organising committee I should like to thank all those who contributed to the organisation of this year's application programme, in particular the programme committee members, the referees and our administrators Fiona Hartree and Linsay Turbert.