The Advancea Kesearch Workshop on Superstrings was held on the campus of the University of Colorado at Boulder from July 27th through August 1, 1987. Since the work of Green and Schwartz in the summer of 1984, string theories have elicited tremendous amount of interest from both theoretical physicists and mathematicians. The objective of the Workshop was to bring together practitioners in the field to discuss the progress and problems, and possible directions of future research. There were ten talks of one hour each and twenty three talks of one-half hour each. The talks covered new...