The contribution of attachment, maternal reported stress, and mother-child interaction to the prediction of teacher-reported behavior problems was examined for a French-Canadian sample of 121 school-age children. Attachment classifications were assigned on the basis of reunion behavior with mother when the children were between 5 and 7 years of age. Maternal reported stress and mother-child interaction patterns were assessed concurrent to the attachment measure, whereas behavior problems were evaluated both at ages 5 to 7 and 7 to 9 years. Security of attachment significantly predicted the likelihood of school-age behavior problems: Controlling/other children were most at risk for both externalizing and internalizing problems across both age periods. Younger ambivalent children presented clinical cut-off levels of externalizing problems, and older avoidant boys had higher internalizing scores. Patterns of maternal-reported stress and mother-child interaction differed across attachment groups and contributed to prediction of school-age behavior problems, partially mediating the relation between attachment and adaptation. Results support the importance of attachment in explaining school-age adaptation and validity of attachment coding for children of this age.