Objective: The purpose of this study was to benchmark the cost efficiency of community care across six child and adolescent mental health services (CAMHS) drawn from different Australian states. Method: Organizational, contact and outcome data from the National Mental Health Benchmarking Project (NMHBP) data-sets were used to calculate cost per "treatment hour" and cost per episode for the six participating organizations. We also explored the relationship between intake severity as measured by the Health of the Nations Outcome Scales for Children and Adolescents (HoNOSCA) and cost per episode. Results: The average cost per treatment hour was $223, with cost differences across the six services ranging from a mean of $156 to $273 per treatment hour. The average cost per episode was $3349 (median $1577) and there were significant differences in the CAMHS organizational medians ranging from $388 to $7076 per episode. HoNOSCA scores explained at best 6% of the cost variance per episode. Conclusions: These large cost differences indicate that community CAMHS have the potential to make substantial gains in cost efficiency through collaborative benchmarking. Benchmarking forums need considerable financial and business expertise for detailed comparison of business models for service provision.