Consistent with behavioral theory such as the theory of planned behavior, numerous studies on determinants of smoking cessation confirmed that attitude, subjective norm, and perceived control each can correlate with intention to quit smoking. However, such main effect findings indicate additive attitudinal, normative, and control effects on quit intention, which is not a truly explanatory account of psychological processes that explain formation of quit intentions among smokers. The purpose of the research reported here was to test one such explanatory process, namely that perceived control moderates attitudinal and normative effects, such that the more smokers feel that they can successfully quit, the stronger attitude and subjective norm affect quit intention. To test the perceived control as moderator hypothesis, the authors submitted data from 3,428 adult smokers to hierarchical regression analyses and demonstrated that in this sample perceived control interacted with attitude (b = .16) and perceived norm (b = .11), f 2 =.04. Furthermore, the authors found that experience with previous quit attempts mattered, such that compared with smokers with relatively short-lived previous quit attempts and smokers who had never tried to quit, the Perceived Control × Attitude interaction in particular was greatest among smokers who had experienced relatively longer periods of remaining quit. Two clear implications of these findings are that behavioral theory should reconsider a moderator role for perceived control, and that smoking cessation interventions should always include a control-building component.