Columbia University Theory Day isto be held twice a year at Columbia University, once in the fall and once in the spring (1992-1994). It attracts 100-150 people mostly from the New York City metropolitan area. Theory Days have two goals. The first is to give an opportunity to theoretical computer scientists to meet. The second is to enable people outside of theory to learn about new developments in theoretical computer science. The Department of Computer Science at Columbia University covered the expense of Theory Day during the first five years, and the department together with the National Science Foundation covered the expense in the following four years.This award helps to cover the expenses of the next six theory days.