OBJECTIVE: The authors examined utilization of the Massachusetts Child Psychiatry Access Project, a mental health telephone consultation service for primary care, hypothesizing that greater use would be related to severe psychiatric diagnoses and polypharmacy. METHODS: The authors examined the association between utilization, defined as the mean number of contacts per patient during the 180 days following the initial contact (July 2008-June 2009), and characteristics of the initial contact, including consultation question, the child's primary mental health problem, psychotropic medication regimen, insurance status, and time of year. RESULTS: Utilization (N=4,436 initial contacts, mean=3.83 contacts) was associated with initial contacts about medication management, polypharmacy, public and private health insurance, and time of year. The child's primary mental health problem did not predict utilization. CONCLUSIONS: Telephone consultation services address treatment with psychotropic medications, particularly polypharmacy. Joint public-private funding should be considered for such public programs that serve privately insured children.