Intention certainty, past behavior, self-schema, anticipated regret, and attitudinal versus normative control all have been found to moderate intention-behavior relations. It is argued that moderation occurs because these variables produce “strong” intentions. Stability of intention over time is a key index of intention strength. Consequently, it was hypothesized that temporal stability of intention would mediate moderation by these other moderators. Participants ( N = 185) completed questionnaire measures of theory of planned behavior constructs and moderator variables at two time points and subsequently reported their exercise behavior. Findings showed that all of the moderators, including temporal stability, were associated with significant improvements in consistency between intention and behavior. Temporal stability also mediated the effects of the other moderators, supporting the study hypothesis.