Objective: To assess aspirations for physical health over 18 months. To examine whether maintained importance of aspirations for physical health mediated and/or moderated the effect of an intensive intervention on long-term tobacco abstinence. Methods: Participants were randomly assigned to an intervention based on self-determination theory or to community care, and provided data at baseline and at 18 and 30 months post-randomization. Results: Aspirations for physical health were better maintained over 18 months among participants in the intervention (mean change = .05), relative to community care (mean change = -.13), t = 2.66, p < .01. Maintained importance of aspirations for physical health partially mediated the treatment condition effects on seven-day point prevalence tobacco abstinence (z' = 1.68, p < .01) and the longest number of days not smoking (z' = 2.16, p < .01), and interacted with treatment condition to facilitate the longest number of days not smoking (beta = .08, p < .05). Conclusion: Maintained importance of aspirations for physical health facilitated tobacco abstinence. Practice implications: Smokers may benefit from discussing aspirations for physical health within autonomy-supportive interventions. Patients may benefit from discussing aspirations during counseling about therapeutic lifestyle change and medication use. (C) 2008 Elsevier Ireland Ltd. All rights reserved.