The effects of deliberative and implemental mindsets--cognitive and motivational states associated with predecisional and postdecisional frames of mind, respectively--were examined in the context of the self-regulation of behavior. Participants who had been induced to deliberate the merits of participating in a specified task formulated more pessimistic expectations about this task than did participants who had been induced to imagine implementing a plan to complete the task. Moreover, participants in the deliberation condition underperformed relative to the participants in the implemental condition, demonstrating that deliberative and implemental thinking can influence behavior as well as cognition. Copyright 2003 Society for Personality and Social Psychology, Inc.