The relations between early infant-mother attachment and children's social competence and behavior problems during the preschool and early school-age period were examined in more than 1,000 children under conditions of decreasing, stable, and increasing maternal parenting quality. Infants' Strange Situation attachment classifications predicted mothers' reports of children's social competence and teachers' reports of externalizing and internalizing behaviors from preschool age through 1st grade. These relations appeared to be mediated by parenting quality; main effects of attachment classification disappeared when effects of parenting quality were controlled. Interactions were also observed. For example, when parenting quality improved over time, teachers rated children with insecure infant-mother attachments lower on externalizing behaviors; when parenting quality decreased, teachers rated insecure children higher on externalizing behaviors. In contrast, children classified as securely attached in infancy did not appear to be affected by declining or improving parenting quality.