Cigarette smoking is a leading cause of mortality and morbidity and a particularly common and intractable addictive disorder. Research shows that nicotine is a sine qua non of tobacco addiction and that it produces the hallmark effects of addictive drugs: sensitization, tolerance, physical dependence, and euphoria/elation. Research on the development of smoking reveals that although smoking prevalence has declined from a peak in the mid-1990s, close to 30% of twelfth graders still smoke. Smoking in adolescents is related to development of physical dependence, ethnicity, impulsivity, affective disorder, and peer influences. However, which of these exerts the greatest causal effects is unknown, and their influence no doubt varies across individuals and across development. Once dependence on tobacco smoking is established, evidence suggests that tobacco motivation is strongly influenced by a reduction in withdrawal symptoms, an expectation of stress reduction, and conditioned reinforcement. Nicotine motivation may also be influenced by modulation in stimulus incentive value.