In Quebec, 20-30% of children in protection services are from blended families. Conjugal unions tend to be unstable in stepfamilies and single parent families that receive child protection services. The children in these families often experience serial transitions with several episodes of family blending. This study analyzed data from 741 children in child protection services to look at the impact of serial transitions on behaviour disorders, anxiety and depression. Results showed that the number of times a family is blended is a stronger predictive factor for difficulties in a child’s adjustment than family type. The accumulation of stress factors associated with family transitions increases the likelihood that children will develop behaviour problems. The study also showed that adjustment is more difficult if children experience a large number of transitions in a short period of time.