A pragmatic comparative effectiveness trial examined whether extending the duration of a cost-effective, intensive tobacco-dependence intervention designed to support autonomy will facilitate long-term tobacco abstinence. Participants were randomly assigned to one of three tobacco-dependence interventions based on self-determination theory, namely, Intensive Treatment (IT; six contacts over 6 months), Extended Need Support (ENS; eight contacts over 12 months) and Harm Reduction (HR; eight contacts over 12 months with medication use if willing to reduce cigarette use by half). Among participants who completed the interventions, analyses revealed beneficial effects of ENS (15.7 versus 3.8%; χ2(1) = 6.92, P < 0.01) and HR (13.6 versus 3.8%; χ2(1) = 5.26, P < 0.05), relative to IT, on 12-month prolonged abstinence from tobacco. Also, analyses revealed beneficial effects of ENS (77.7 versus 43.0%; χ2(1) = 24.90, P < 0.001) and HR (84.0 versus 43.0%; χ2(1) = 37.41, P < 0.001), relative to IT, on use of firstline medications for smoking cessation. Hence, two new interventions were found to be efficacious particularly among participants who completed the interventions. Smokers who stay in treatment for an additional 6 months may benefit from an additional two contacts with practitioners, and thus it seems reasonable for policy makers to offer additional contacts given the health benefits associated with prolonged tobacco abstinence.