Variations in amounts of nonparental care across infancy, preschool, early elementary school, and early adolescence were examined in a longitudinal sample (N = 438). Of interest was (a) continuity in use of the different arrangements, (b) whether the arrangements were additively and cumulatively associated with children's externalizing behavior problems, and (c) whether predictive relations were accounted for by social-ecological (socioeconomic status, mothers' employment status, marital status) and social-experiential (parenting quality, exposure to aggressive peers) factors. Correlations among overall amounts of care provided little evidence of cross-time continuity. Consistent with the cumulative risk perspective, Grade 1 self-care and Grade 6 unsupervised peer contact incrementally predicted Grade 6 externalizing problems. Most of the predictive associations were accounted for by family background and social relationship factors.