['To examine the rates and predictors of mental health services use for a nationally representative cohort of youths who had been investigated for alleged maltreatment.', 'Data came from caregiver and caseworker baseline and 18-month interviews in the second National Survey of Child and Adolescent Well-being. These interviews took place from March 2008 to September 2008 and September 2010 to March 2011. Data on family and child characteristics and service use were gathered and examined by using weighted univariate and multivariate analyses.', 'Children had numerous challenges: 61.8% had a previous report of maltreatment, 46.3% had poor socialization skills, and 23.9% had a mental health problem measured by the Child Behavior Checklist (CBCL). At baseline, 33.3% received some mental health service and this varied by age, with younger children receiving fewer services. This percentage decreased to 30.9% at the 18-month follow-up, although the youngest children had increases in services use. For younger children, race/ethnicity, out-of-home placement, chronic physical health problems, low adaptive behaviors, and CBCL scores in the clinical range were related to use. For children ≥ 11, out-of-home placement, high CBCL scores, and family risk factors predicted services use at 18 months.'] Do mental health services use by children investigated by child welfare agencies?