In the United States, one of the great concerns in the obesity epidemic is the disparity among racial and ethnic groups in the prevalence of obesity. Data from the Fragile Families and Child Well-being Study represent a birth cohort from 75 hospitals across 20 large cities in 15 states. At 3 years of age, 26% of Hispanic children were obese compared with 16% of black children and 15% of white children. This higher prevalence of obesity in Hispanic children was not explained by maternal education, household income, or children's food security status. Other yet unidentified factors must be explored to explain these differences, particularly since they occur so early in life.