We examined the relationship of smoking history, motivation, social support, and stress to initial cessation and long-term abstinence in a sample of 402 smokers who participated in a worksite smoking cessation program. Compared to nonquitters, smokers who initially stopped smoking expected less difficulty quitting, had previously abstained for longer periods, and had a higher desire to quit. Long-term abstainers were lighter smokers and had more social support and less stress than relapsers. The differences in the predictors of initial cessation and long-term abstinence support the concept of a staged cessation process. The results suggest that intraindividual factors are particularly important early in the process, whereas environmental factors are more important during the later, maintenance stage. These findings are consistent with a biopsychosocial model of cessation and relapse and support multicomponent interventions.