This article compares mental health service need and use among three groups of children: those with a history of foster care placement, those in contact with departments of social services but never in placement, and those from impoverished families who have not been in contact with social services. Data come from a longitudinal epidemiologic study of mental health problems and service use. All three groups show very high rates of mental health problems, but children in foster are or in contact with social services are significantly more likely than children living in poverty to receive mental health services.