A smoker self-concept and an abstainer self-concept are individual difference variables that have been shown to predict smoking cessation. We examined whether these self-concept constructs changed as a function of participating in a clinic-based smoking cessation program and, specifically, whether these changes occurred differentially between posttreatment smokers and abstainers. Subjects completed the Smoker Self-concept scale and the Abstainer Self-concept scale at three time points: pretreatment, posttreatment, and 3 months' posttreatment. Smoking status was assessed and biochemically verified directly after quit day and 3 months' posttreatment. Results indicated that abstainers' smoker self-concept decreased more precipitously over time compared to smokers'. Abstainers showed consistent increases over time in their abstainer self-concept, and smokers showed increases followed by decreases to pretreatment levels. Clinical implications are discussed.