This book constitutes the refereed proceedings of the 27th European Conference on Information Retrieval Research, ECIR 2005, held in Santiago de Compostela, Spain in March 2005.

The 34 revised full papers presented together with 2 invited keynote papers and 17 selected poster papers were carefully reviewed and selected from 124 papers submitted. The papers are organized in topical sections on peer-to-peer, information retrieval models, text summarization, information retrieval methods, text classification and fusion, user studies and evaluation, multimedia retrieval, and Web information retrieval.