GeoCLEF is an evaluation initiative for testing queries with a geographic specification in large set of text documents. GeoCLEF ran a regular track for the third time within the Cross Language Evaluation Forum (CLEF) 2008. The purpose of GeoCLEF is to test and evaluate cross-language geographic information retrieval (GIR). GeoCLEF 2008 consisted of two sub tasks. A search task ran for the third time and a Wikipedia pilot task (GikiP) was organized for the first time. For the GeoCLEF 2008 search task, twenty-five search topics were defined by the organizing groups for searching English, German and Portuguese document collections. Topics were developed also for English, German and Portuguese. Many topics were geographically challenging. Eleven groups submitted 131 runs. The groups used a variety of approaches, including sample documents, named entity extraction and ontology based retrieval. The evaluation methodology and results are presented in the paper. Categories and Subject Descrip...