This book constitutes the thoroughly refereed postproceedings of the 4th Workshop of the Cross-Language Evaluation Forum, CLEF 2003, held in Trondheim, Norway in August 2003. The 61 revised papers presented together with an introduction were carefully reviewed and selected for inclusion in the book. The papers are organized in topical sections on mainly cross-language experiments, mono lingual experiments, domain-specific document retrieval, interactive cross-language retrieval, cross-language question answering, cross-language image retrieval, and cross-language spoken document retrieval.