Charles Clarke is a Professor in the School of Computer Science at the University of Waterloo. His research interests include information retrieval, search engines, database systems and software development tools. He has published on a wide range of topics, including papers related to question answering, XML, program analysis, filesystem search, user interfaces, statistical natural language processing, and the evaluation of information retrieval systems. He was a Program Co-Chair of the 2007 ACM SIGIR Conference on Research and Development in Information Retrieval; he was the General Co-Chair of SIGIR in 2003. He received his Ph.D. from Waterloo in 1996. From 1996 to 1999 he was an Assistant Professor in the Department of Electrical and Computer Engineering at the University of Toronto. He has previously held software development positions at a number of computer consulting and engineering firms. In 2006 he spent a sabbatical at Microsoft, where he was involved in the development of their Web search engine.