The Evidence Synthesis Program (ESP) Coordinating Center is responding to a request from the Office of Mental Health and Suicide Prevention (OMHSP) for an Evidence Brief on treatment of comorbid mental health conditions, or mental health conditions comorbid with a traumatic brain injury, substance use disorder, or chronic pain among Veterans and military Service members. Findings from this Evidence Brief will be used to inform the development of a clinical provider toolkit, as required by the Commander John Scott Hannon Veterans Mental Health Care Improvement Act (S.785 2019). The toolkit is intended to enhance clinical provider training in delivery of comprehensive care for Veterans and military Service members with comorbid conditions.