This book constitutes the refereed proceedings of the 4th International Conference of the CLEF Initiative, CLEF 2013, held in Valencia, Spain, in September 2013. The 32 papers and 2 keynotes presented were carefully reviewed and selected for inclusion in this volume. The papers are organized in topical sections named: evaluation and visualization; multilinguality and less-resourced languages; applications; and Lab overviews.weiterlesen