Substance use and mental health disorders remain significant behavioral health concerns in the United States and other Western nations. Nearly half of the 20.3 million adults with substance use disorders in the US have a co-occurring mental illness. Despite growing research support, integrated treatment by providers with expertise in both mental health and substance use is critically lacking. As part of a co-occurring disorders (COD) training initiative in the USA, this study investigated providers' (n = 438) past training, current COD service provision, and future training needs. Specifically, we examined the extent to which social workers were prepared to treat individuals with COD compared to alcohol and drug counselors. Unsurprisingly, social workers reported receiving significantly more mental health related training, while alcohol and drug counselors reported more substance use related training. Alcohol and drug counselors reported significantly more COD-specific training including general COD, psychopharmacology, COD treatment, and relapse prevention. Social workers were significantly more likely than alcohol and drug counselors to report wanting more training in substance use disorders and culturally-specific intervention techniques. These findings suggest that tailored training and licensure changes are needed to enhance social workers' capacity for competent COD treatment. © 2014 © 2014 Taylor & Francis.