Internationally adopted children present more behavior problems than non-adopted children and are overrepresented in mental health services. These problems are related to children's pre-adoption environment, but adoptive families' functioning and characteristics may also affect the development of behavior problems in adopted children. The aim of this longitudinal study was to examine the effect of pre-adoption adversity and parenting stress on children's behavior problems at school-age. Our sample consisted of 95 children adopted during infancy. Children's health and developmental status was evaluated soon after arrival in their adoptive country. Their behavior problems were assessed at age 7 using a self-report measure, the Dominic Interactive, and the CBCL completed by the mothers. Parenting stress was measured using the PSI. Children's characteristics at time of adoption were significantly related to their behavior problems at school-age, and maternal stress was found to have a mediating effect on this relationship. (Contains 4 tables.)