The transtheoretical model for intentional behavior change is described, and pharmacists' use of the model in smoking-cessation interventions is discussed. This model combines elements of theories used in psychotherapy and behavior modification. In the model are five stages (precontemplation, contemplation, preparation, action, and maintenance) that describe when behavior change occurs. To be most effective, a health care provider's interventions should match the patient's stage of change. The model also includes 10 cognitive and behavioral processes that describe how change occurs while a person is moving among the stages. The processes (social liberation, dramatic relief, helping relationships, consciousness-raising, environmental reevaluation, reinforcement management, self-reevaluation, stimulus control, counterconditioning, and self-liberation) define change in terms of the coping strategies used. Before intervening, the pharmacist needs to ask questions about the patient's behavior that will identify the stage. If smokers in the precontemplation stage are receiving medications for chronic diseases, pharmacists can make them aware of the negative effects of smoking on their specific conditions. People in the contemplation stage are open to education about smoking and health, and those in the preparation stage are ready to set goals and choose methods for cessation. Smokers in the action stage are attempting to quit. Pharmacists can offer support, reinforcement, and guidance to people in the action and maintenance stages. Pharmacists can use the transtheoretical model to categorize patients by their stage of change and then devise and deliver appropriate and individualized interventions.