The great majority of children receiving intervention from child welfare and protection services (CWS) in Norway live at home. The purpose of this study was to assess mental health problems among these children. Data stem from a population-based study, the Bergen child study, conducted in 2006. Of a sample consisting of 4,162 children in the fifth to seventh grades, 82 children were CWS clients who lived at home. Compared with their peers, the CWS children had significantly higher scores on emotional problems, hyperactivity, conduct problems, peer problems, and total difficulties (child and parent reports on the Strengths and Difficulties Questionnaire). The relationship between being a CWS client and total difficulties remained significant when socio-demographic variables were controlled for. Even though the results indicate that child welfare clients have more contact with child and adolescent mental health service than earlier assumed, the results emphasise the need for strong collaboration between CWS and mental health services and the need for CWS to include other types of interventions in addition to financial support.