Objective. The efficacy of individualized, community-based physical activity as an adjunctive smoking cessation treatment to enhance long-term smoking cessation rates was evaluated for the Lifestyle Enhancement Program (LEAP). Methods. The study was a two-arm, parallel-group, randomized controlled trial. All participants (n = 392) received cessation counseling and a nicotine patch and were randomized to physical activity (n = 199; YMCA membership and personalized exercise programming from a health coach) or an equal contact frequency wellness curriculum (n = 193). Physical activity treatment was individualized and flexible (with each participant selecting types of activities and intensity levels and being encouraged to exercise at the YMCA and at home, as well as to use “lifestyle” activity). The primary outcome (biochemically verified prolonged abstinence at 7-weeks (end of treatment) and 6- and 12-months postcessation) and secondary outcomes (7-day point prevalent tobacco abstinence (PPA), total minutes per week of leisure time physical activity and strength training) were assessed at baseline, 7 weeks, 6 months, and 12 months. Results. Prolonged abstinence in the physical activity and wellness groups was 19.6% and 25.4%, respectively, at 7-weeks, 15.1% and 16.6% at 6-months, and 14.1% and 17.1% at 12 months (all between-group P values >0.18). Similarly, PPA rates did not differ significantly between groups at any follow-up. Change from baseline leisure-time activity plus strength training increased significantly in the physical activity group at 7 weeks (P = 0.04). Across treatment groups, an increase in the number of minutes per week in strength training from baseline to 7 weeks predicted prolonged abstinence at 12 months (P ≤ 0.001). Further analyses revealed that social support, fewer years smoked, and less temptation to smoke were associated with prolonged abstinence over 12 months in both groups. Conclusions. Community-based physical activity programming, delivered as adjunctive treatment with behavioral/pharmacological cessation treatment, did not improve long-term quit rates compared to adjunctive wellness counseling plus behavioral/pharmacological cessation treatment. This trial is registered with https://beta.clinicaltrials.gov/study/NCT00403312, registration no. NCT00403312.