Although attitudes are commonly conceived to be tendencies to specific types of action, the relationship between attitude change and subsequent behavior has been investigated in only a few research studies. The importance of this neglected scientific problem and the meagerness of the data as yet available, which run somewhat contrary to prevalent expectations, call for concerted research efforts in the future. Leon Festinger is Professor of Psychology at Stanford University. This article was his presidential address for the Division of Personality and Social Psychology at the meetings of the American Psychological Association in September 1963.