OBJECTIVE: To determine 1) whether participants in the Spanish Diabetes Self-Management Program (SDSMP), when compared at 6 months to randomized control subjects, would demonstrate improvements in health status, health behaviors, and self-efficacy; and 2) whether SDSMP participants receiving monthly automated telephone reinforcement would maintain improvements at 18 months better than those not receiving reinforcement. RESEARCH DESIGN AND METHODS: A total of 567 Spanish-speaking adults with type 2 diabetes were randomized to a usual-care control group or 6-week community-based, peer-led SDSMP. SDSMP participants were re-randomized to receive 15 months of automated telephone messages or no reinforcement. A1C was measured at baseline and 6 and 18 months. All other data were collected by self-administered questionnaires. RESULTS: At 6 months SDSMP participants compared with control subjects demonstrated improvements in A1C (-0.4%), health distress, symptoms of hypo- and hyperglycemia, and self-efficacy (P < 0.05). At 18 months all improvements persisted (P < 0.05). SDSMP participants also demonstrated improvements in self-rated health and communication with physicians, had fewer emergency room visits (-0.18 visits in 6 months, P < 0.05), and trended toward fewer visits to physicians. At 18 months the only difference between reinforced and nonreinforced participants was increased glucose monitoring for the reinforcement group. CONCLUSIONS: The SDSMP demonstrated effectiveness in lowering A1C and improving health status. Reinforcement did not add to its effectiveness. Given the high needs of the Spanish-speaking population, the SDSMP deserves consideration for implementation.