AbstractAlthough smoking-cessation rates have continued to increase, the vast majority of smokers who quit eventually relapse. Between 1974 and 1985, over 1.3 million smokers quit during each of those years. However, 75% to 80% of those individuals resumed smoking within six months. This article describes the dynamic phenomenon of smoking relapse within the context of cyclical episodes of smoking and quitting during an individual's lifetime. Theories of the determinants of smoking relapse are reviewed and methods designed to prevent relapse are described. Smoking relapse is discussed in terms of three aspects of tobacco addiction: (1) biological-addiction mechanisms, (2) conditioning processes, and (3) cognitive-social learning factors. The major determinants of smoking relapse are reviewed, including nicotine withdrawal, stress, weight gain, social influences, conditioning factors, causal attributions, and environmental variables. A transtheoretical-developmental model is explored in the longitudinal investigation of the natural history of slips (lapses) and relapse episodes. Relapse prevention interventions are described that emphasize self-awareness, self-regulation, self-efficacy, affect regulation, social support, and lifestyle balance. Recent developments in pharmacological adjuncts to treatment are also examined. It is concluded that innovative relapse prevention methods need to be designed for hard-core smokers with histories of cessation failures, substance abuse and/or psychiatric impairment. These and other recommendations for future research on smoking relapse and relapse prevention are discussed.