OBJECTIVE—The objective of this study was to determine if a community-based modified Diabetes Prevention Program Group Lifestyle Balance (GLB) intervention, for individuals with metabolic syndrome, was effective in decreasing risk for type 2 diabetes and cardiovascular disease (CVD) in an urban medically underserved community, and subsequently to determine if improvements in clinical outcomes could be sustained in the short term. RESEARCH DESIGN AND METHODS—This nonrandomized prospective intervention study used a one-group design to test the effectiveness of a community-based GLB intervention. Residents from 11 targeted neighborhoods were screened for metabolic syndrome (n = 573) and took part in a 12-week GLB intervention (n = 88) that addressed safe weight loss and physical activity. RESULTS—A marked decline in weight (46.4% lost ≥5% and 26.1% lost ≥7%) was observed in individuals after completion of the intervention. Of these subjects, 87.5% (n = 28) and 66.7% (n = 12) sustained the 5% and 7% reduction, respectively, at the 6-month reassessment. Over one-third of the population (43.5%, n = 30) experienced improvements in one or more component of metabolic syndrome, and 73.3% (n = 22) sustained this improvement at the 6-month reassessment. Additional improvements occurred in waist circumference (P < 0.009) and blood pressure levels (P = 0.04) after adjustment for age, sex, race, mean number of GLB classes attended, and time. CONCLUSIONS—Adults in an urban medically underserved community can decrease their risk for type 2 diabetes and CVD through participation in a GLB intervention, and short-term sustainability is feasible. Future research will include long-term follow-up of these subjects.