This book constitutes the thoroughly refereed proceedings of the 10th Workshop of the Cross Language Evaluation Forum, CLEF 2010, held in Corfu, Greece, in September/October 2009.The volume reports experiments on various types of multimedia collections. It is divided into threemain sections presenting the results of the following tracks: Interactive Cross-Language Retrieval (iCLEF), Cross-Language Image Retrieval (ImageCLEF), and Cross-Language Video Retrieval (VideoCLEF).