OBJECTIVE: Limited data exist on the association between in utero exposure to maternal diabetes and obesity and type 2 diabetes in diverse youth. These associations were explored in African-American, Hispanic, and non-Hispanic white youth participating in the SEARCH Case-Control Study. RESEARCH DESIGN AND METHODS: A total of 79 youth with type 2 diabetes and 190 nondiabetic control youth aged 10-22 years attended a research visit. In utero exposures to maternal diabetes and obesity were recalled by biological mothers. RESULTS: Youth with type 2 diabetes were more likely to have been exposed to maternal diabetes or obesity in utero than were nondiabetic control youth (P < 0.0001 for each). After adjusting for offspring age, sex, and race/ethnicity, exposure to maternal diabetes (odds ratio [OR] 5.7 [95% CI 2.4-13.4]) and exposure to maternal obesity (2.8 [1.5-5.2]) were independently associated with type 2 diabetes. Adjustment for other perinatal and socioeconomic factors did not alter these associations. When offspring BMI was added, the OR for the association between in utero exposure to obesity and type 2 diabetes was attenuated toward the null (OR 1.1 [0.5-2.4]). Overall, 47.2% (95% CI 30.9-63.5) of type 2 diabetes in youth could be attributed to intrauterine exposure to maternal diabetes and obesity. CONCLUSIONS: Intrauterine exposures to maternal diabetes and obesity are strongly associated with type 2 diabetes in youth. Prevention efforts may need to target, in addition to childhood obesity, the increasing number of pregnancies complicated by obesity and diabetes.