This book contains the first collection of papers addressing recent developments in the design of information retrieval systems using language modeling techniques. Language modeling approaches are used in a variety of other language technologies, such as speech recognition and machine translation, and the book shows that applications such as Web search, cross-lingual search, filtering, and summarization can be described in the same formal framework. The book is intended primarily for researchers and advanced graduate students working in the language technologies areas of computer science or information science.