Data from the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care, a prospective, longitudinal study involving 933 children, were used to examine relations between cumulative participation in 5 types of out-of-school care (before- and after-school programs, extracurricular activities, sitters, fathers, and nonadult care) and child developmental outcomes in the latter part of first grade (approximately age 7 years). Children who consistently participated in extracurricular activities during kindergarten and first grade obtained higher standardized test scores than children who did not consistently participate in these activities, controlling for child and family factors and children's prior functioning. Participation in other types of out-of-school care was not associated with child functioning in first grade when background factors were controlled.