Objectives: To explore the associations between shelter proximity and real-time affect during a specific smoking quit attempt among 22 homeless adults. Methods: Affect was measured via 485 smartphone- based Ecological Momentary Assessments randomly administered during the weeks immediately before and after the quit day, and proximity to the shelter was measured via GPS. Adjusted linear mixed model regressions examined associations between shelter proximity and affect. Results: Closer proximity to the shelter was associated with greater negative affect only during the post-quit attempt week (p = .008). All participants relapsed to smoking by one week postquit attempt. Conclusions: Among homeless smokers trying to quit, the shelter may be associated with unexpected negative affect/stress. Potential intervention applications are suggested. Copyright (c) PNG Publications. All rights reserved.