We employed a national survey of child psychiatrists to examine typical prescribing practices for children with anxiety, depression, and disruptive behavior disorders. We examined the extent to which polypharmacy and off-label prescribing occur in routine practice and the degree to which child characteristics, child psychiatrist characteristics, and medication availability may influence these prescribing practices. We found that child psychiatrists most often prescribed medications that were on-label according to U.S. Food and Drug Administration (FDA) guidelines, and that they were progressively less likely to choose medications with partial approval (i.e., medications having pediatric approval but not for the patient's age or problem type), and then medications with no pediatric approval. We also found that prescribing multiple concomitant medications was the norm. We employed best subsets regression to determine the best theoretically relevant predictors to explain polypharmacy and off-label prescribing and found that the best fitting model only included number of child diagnoses. These findings suggest that comorbidity is an important issue in the pharmacotherapy of children with mental health disorders and one that must be addressed in future clinical trials.