To evaluate child-care effects on young children's self-control, compliance, and problem behavior, children enrolled in the NICHD Study of Early Child Care were tested and observed in the laboratory and in child care at 24 and 36 months, and mothers and caregivers completed questionnaires. Indicators of child-care quantity, quality, stability, type, and age of entry, along with measures of family background, mothering, and child characteristics obtained through the first 3 years of life were used to predict 2 and 3 year child functioning. Results revealed (1) mothering to be a stronger and more consistent predictor of child outcomes than child care; (2) little evidence that early, extensive, and continuous care was related to problematic child behavior, in contrast to results from earlier work; (3) that among the child-care predictors, child-care quality was the most consistent predictor of child functioning, although limited variance could be explained by any (or all) child-care variables; and (4) that virtually none of the anticipated interactions among child-care factors or between them and family or child measures proved significant.