Patients in a low-income community health center with Type 2 diabetes (N = 81) taking a one-day education workshop as part of their diabetes medical management were randomly assigned either to education alone or to a combination of education and acceptance and commitment therapy (ACT). Both groups were taught how to manage their diabetes, but those in the ACT condition also learned to apply acceptance and mindfulness skills to difficult diabetes-related thoughts and feelings. Compared with patients who received education alone, after 3 months those in the ACT condition were more likely to use these coping strategies, to report better diabetes self-care, and to have glycated hemoglobin (HbA-sub(1C)) values in the target range. Mediational analyses indicated that changes in acceptance coping and self-management behavior mediated the impact of treatment on changes in HbA-sub(1C).