Objective: Many treatment-seeking smokers have difficulty quitting and maintaining abstinence. Trait impulsivity versus self-control is relevant to this problem. However, impulsivity is a multifaceted construct, and different measures emphasize different parts of it. This study compared 2 self-report measures of self-control versus impulsiveness as predictors of smoking cessation. One measure taps a very specific tendency to respond impulsively when experiencing emotions. The other taps overall self-control without reference to emotional states. Method: Adult smokers (N = 116) recruited from the community participated in a group-based smoking cessation intervention. The sample was racially/ethnically diverse, mostly male, middle aged, single, low income, and moderately nicotine dependent. Self-reports on scales titled Reflexive reaction to feelings and Self-control were completed at entry. Seven-day point prevalence abstinence (ppa) was assessed at end-of-therapy (EOT) and at 3- and 6-month follow-ups. A generalized estimating equation (GEE) tested overall relationships of the self-report scales with 7-day ppa across the assessments. Results: Bivariate analyses revealed inverse associations between Reflexive reaction to feelings and 7-day ppa; a positive association emerged between Self-control and 7-day ppa only at EOT. A GEE found that elevated scores on Reflexive reaction to feelings predicted failure in smoking cessation across the study period (adjusted odds ratio [AOR] = 0.69 [0.49–0.96], p = .03) and that Self-control scores did not do so significantly (AOR = 1.26 [0.80–1.99], p = .32). Conclusions: Results add to a literature suggesting the importance of emotion-related impulsivity to behavioral problems by showing its relevance to smoking cessation in treatment-seekers.