This book constitutes the refereed proceedings of the 7th European Conference on Case-Based Reasoning, ECCBR 2004, held in Madrid, Spain in August/September 2004.The 56 revised full papers presented together with an invited paper and the abstract of an invited talk were carefully reviewed and selected from 85 submissions. All current issues in case-based reasoning, ranging from theoretical and methodological issues to advanced applications in various fields are addressed.