The ?fth campaign of the Cross-Language Evaluation Forum (CLEF) for Eu- pean languages was held from January to September 2004. Participation in the CLEF campaigns has increased each year and CLEF 2004 was no exception: 55 groups submitted results for one or more of the di?erent tracks compared with 42 groups in the previous year. CLEF 2004 also marked a breaking point with respect to previous campaigns. The focus was no longer mainly concentrated on multilingual document retrieval as in previous years but was diversi?ed to include di?erent kinds of text retrieval across languages (e. g. , exact answers in the question-answering track) and retrieval on di?erent kinds of media (i. e. , not just plain text but collections containing image and speech as well). In ad- tion, increasing attention was given to issues that regard system usability and user satisfaction with tasks to measure the e?ectiveness of interactive systems or system components being included in both the cross-language question - swering and image retrieval tasks with the collaboration of the coordinators of the interactive track. The campaign culminated in a two-and-a-half-day workshop held in Bath, UK, 15-17 September, immediately following the 8th European Conference on Digital Libraries. The workshop was attended by nearly 100 researchers and s- tem developers.

This book constitutes the thoroughly refereed postproceedings of the 6th Workshop of the Cross-Language Evaluation Forum, CLEF 2005, held in Vienna, Austria in September 2005.

The 111 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 multilingual textual document retrieval, cross-language and more, monolingual experiments, domain-specific information retrieval, interactive cross-language information retrieval, multiple language question answering, cross-language retrieval in image collections, cross-language speech retrieval, multilingual Web track, cross-language geographical retrieval, and evaluation issues.

The fourth campaign of the Cross-language Evaluation Forum (CLEF) for European languages was held from January to August 2003. Participation in this campaign showed a slight rise in the number of participants from the previous year, with 42 groups submitting results for one or more of the different tracks (compared with 37 in 2002), but a steep rise in the number of experiments attempted. A distinctive feature of CLEF 2003 was the number of new tracks and tasks that were offered as pilot experiments. The aim was to try out new ideas and to encourage the development of new evaluation methodologies, suited to the emerging requirements of both system developers and users with respect to today s digital collections and to encourage work on many European languages rather than just those most widely used. CLEF is thus gradually pushing its participants towards the ultimate goal: the development of truly multilingual systems capable of processing collections in diverse media. The campaign culminated in a two-day workshop held in Trondheim, Norway, 21 22 August, immediately following the 7th European Conference on Digital Libraries (ECDL 2003), and attended by more than 70 researchers and system developers. The objective of the workshop was to bring together the groups that had participated in the CLEF 2003 campaign so that they could report on the results of their experiments."

This book constitutes the thoroughly refereed post-proceedings of the Second Workshop of the Cross-Language Evaluation Forum, CLEF 2001, held in Darmstadt, Germany in September 2001.The 35 revised full papers presented together with two introductory survey articles and a comprehensive appendix were carefully improved during the round of reviewing and selections. The papers are organized in topical sections on systems evaluation experiments, mainly cross-language, monolingual experiments, interactive issues, and evaluation issues and results.