As part of the National Comorbidity Initiative, the Australian Government Department of Health and Ageing funded the National Drug and Alcohol Research Centre (NDARC) to develop guidelines on the management of co-occurring mental health conditions in alcohol and other drug (AOD) treatment settings. The Guidelines were developed based on a comprehensive review of the best available evidence and the experience of an expert panel of academic researchers, clinicians, consumers and carers. They aim to: increase AOD workers’ knowledge and awareness of mental health conditions; ii) improve the confidence and skills of AOD workers working with clients with comorbid mental health conditions; iii) provide guiding principles for working with clients with comorbid mental health conditions; iv) improve AOD workers’ ability to identify mental health conditions; v) provide practical information on the management of comorbid mental health conditions; vi) provide information regarding the treatment of comorbid mental health conditions and referral processes; and vii) provide resources that may be used to facilitate all of the above. This paper aims to outline the Guidelines and their development, and provide a summary of their contents.