Evidence concerning the developmental correlates of nonmaternal care in the first year of life are examined with respect to infant-mother attachment and subsequent social development. Even though the evidence is not without its inconsistencies, a circumstantial case, consistent with attachment theory, can be made that extensive infant day care experience is associated with insecure attachment during infancy and with heightened aggressiveness and noncompliance during the preschool and early school-age years. It is concluded that entry into some nonmaternal care arrangement in the first year for more than 20 hours per week may be a risk factor in the emergence of developmental difficulties. The consequences of such risk are best understood in the context of characteristics of the child, the family, and the caregiving milieu. A 90-item reference list concludes the document. (Author/PCB)