The IEEE Communication Theory Workshop is held yearly at various sites in the United States. The 1990 Workshop is the 20th in the series and will be held in Ojai, California, on June 24-27. Sessions at the workshop consist solely of invited papers and the speakers generally represent the highest echelon of the communications research community. The purpose of the workshop is to present primarily new results in all areas of communication theory; including, for example, modulation and coding, signal processing for ISDN, optical communications, and multi-user communications. These topics are highly important to both basic theoretical advances in digital communications and application to commercial telecommunications. The NSF award is used to provide travel funds for U.S. scientists and engineers who could not otherwise attend due to lack of funding.