This study identified correlates and developmental antecedents that distinguish popular-aggressive elementary school children from other youth. Drawing on the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (N = 1022), popular-aggressive children were identified through teacher ratings over Grades 3–6. Potential correlates included social competence as rated by observers, mothers, and teachers. Potential developmental antecedents included cognitive functioning, maternal sensitivity, and participation in child care through age 4.5. Multinomial regressions allowed for the determination of group differences net of covariates such as gender, ethnicity, maternal education, and income-to-needs. Results showed that popular-aggressive elementary school children were distinguished from other youth as having had an extensive child-care history. Discussion focuses on developmental associations between child-care quantity and aggression.