Therapists assessing and treating children in foster care face unique issues, due to the complicated relational system generated by a foster placement. At a minimum, the mental health clinician must negotiate a role relative to the foster family, especially the foster parents, biological parents, and the Child Protective Service Agency (CPS) represented by the caseworker. The system of relationships and the ambiguous status of the child in foster care affects both the range of issues that need to be assessed to identify factors contributing to a child's problems and the context of possible interventions. The therapeutic relationship with the child is also affected by the child's understanding of and feelings about the connections, or lack of them, between the therapist and other meaningful adults in the child's life. This paper considers issues affecting the role of the therapist relative to each relationship and then considers the broader role of the therapist as an intervener in the foster care and protective service system.