Young people with comorbid disorders frequently come to the attention of a diverse range of service systems (e.g., health, social welfare, educational, and criminal justice systems), and present a significant challenge to service providers. Little research has been conducted examining the confidence of workers in responding to young clients with comorbidity. The evidence that does exist suggests they lack appropriate training and support, feel overwhelmed and fearful when dealing with comorbid clients, and have difficulty accessing appropriate training or supervision. In order to address this issue, the Australian Government Department of Health funded researchers at the Centre of Research Excellence in Mental Health and Substance Use at the National Drug and Alcohol Research Centre to conduct a scoping exercise to evaluate the training and support needs of clinicians working with young clients who have AOD and/or mental health conditions. The primary aim of the scoping exercise was to provide recommendations for workforce development. By improving the capacity of the workforce to intervene with this population, the standard of care may be improved, and the enduring disability associated with mental health and AOD disorders may be reduced.