This book constitutes the refereed proceedings of the Second International Conference on Artificial Immune Systems, ICARIS 2003, held in Edinburgh, UK in September 2003.The 27 revised full papers presented were carefully reviewed and selected from 41 submissions. The book presents the first coherent account of the state of the art in artificial immune systems reserch. The papers are organized in topical sections on applications of artificial immune systems, immunocomputing, emerging metaphors, augmentation of artificial immune systems algorithms, theory of artificial immune systems, and representations and operators.