['Children involved with child welfare systems are at high risk for emotional and behavioral problems. Many children with identified mental health problems do not receive care, especially ethnic/minority children.', 'To examine how patterns of specialty mental health service use among children involved with child welfare vary as a function of the degree of coordination between local child welfare and mental health agencies.', 'Specialty mental health service use for 1 year after contact with child welfare was examined in a nationally representative cohort of children aged 2 to 14 years. Predictors of service use were modeled at the child/family and agency/county levels. Child- and agency-level data were collected between October 15, 1999, and April 30, 2001.', 'Ninety-seven US counties.', 'A total of 2823 child welfare cases (multiple informants) from the National Survey of Child and Adolescent Well-being and agency-level key informants from the participating counties.', 'Specialty mental health service use during the year after contact with the child welfare system.', 'Only 28.3% of children received specialty mental health services during the year, although 42.4% had clinical-level Child Behavior Checklist scores. Out-of-home placement, age, and race/ethnicity were strong predictors of service use rates, even after controlling for Child Behavior Checklist scores. Increased coordination between local child welfare and mental health agencies was associated with stronger relationships between Child Behavior Checklist scores and service use and decreased differences in rates of service use between white and African American children.'] Do contextual predictors of mental health service use among children open to child welfare?