Relapse is by far the most likely outcome of any smoking cessation attempt, even those made with the benefit intensive psychosocial treatment and pharmacotherapy. The present article briefly reviews the epidemiology of smoking and self-quitting, the outcome data for major forms of behavioral and pharmacologic smoking cessation treatments, and what is known about the natural history of relapse and recovery among treated smokers. A recent trend in smoking relapse research has been to study the dynamics of key motivational processes, such as withdrawal symptoms, negative affect, and craving, in the laboratory and in smokers' natural environments. This literature is also briefly reviewed, with an emphasis on how such investigations may reveal the limitations of current cessation treatments. Finally, three significant research themes that are likely to be important in future relapse research are highlighted--the possible "hardening" of the smoking population, the potential for developmental research to deepen our understanding of smoking motivation, and the promise of molecular genetic studies for advancing treatment and our understanding of relapse.