The theory of planned behavior (TPB) provides a framework for designing and evaluating behavior change interventions. The theory postulates a sequence of effects from behavioral, normative, and control beliefs regarding the behavior to attitudes and subjective norms, which – moderated by perceived behavioral control – lead to the formation of a behavioral intention. Intention is proposed to be carried out to the extent that the behavior is under volitional control. For an intervention to motivate the desired behavior, it must influence behavioral, normative, and/or control beliefs; and, to support implementation of the behavior, it must ensure sufficient perceived and actual behavioral control. Practical steps for the design and evaluation of a TPB-based intervention are described. These include research to elicit accessible beliefs; construction and validation of a TPB questionnaire; confirmation of the structural TPB model; and a preliminary test of the intervention’s ability to change the targeted variables. In the final phase, the intervention is administered and its effects are evaluated by examining changes in behavior and its theoretical determinants. Research has supported the predictive validity of the TPB and its utility as a framework for behavior modification. Future research is needed to identify additional effective strategies to change TPB determinants.