SLIPS OR UNINTENDED ACTIONS HAVE BOTH THEORETICAL AND APPLIED IMPORTANCE, BY PROVIDING INSIGHT INTO POSSIBLE UNDERLYING MECHANISMS OF BEHAVIOR AND BECAUSE OF THEIR REAL-WORLD CONSEQUENCES. Several collections of slips are examined and an outline for a theory of action is proposed, based on selection of appropriate schemas, their activation in memory, and triggering by appropriate conditions, with errors possible at each stage. A categorization of slips is presented based on this outline. Finally, the role of feedback and cybernetic theories of human performance are discussed. (Author)