The usefulness of measuring implementation intentions in the context of the theory of planned behavior (TPB) was explored among 112 Norwegian college students. They responded to a questionnaire measuring past behavior, perceived behavioral control, behavioral intentions, implementation intentions, and actual performance of regular exercising and recycling of drinking cartons. Implementation intentions were measured using five items relating to recycling and four items relating to exercise, which showed satisfactory internal consistencies. Consistent with the main prediction, the presence of implementation intentions was related to performing the two behaviors, although behavioral intentions were the strongest determinant for both behaviors. The results suggest that the TPB may benefit from inclusion of the concept of implementation intentions to provide a more complete understanding of the psychological process in which motivation is translated into action.