Support and treatment for military veterans and active duty service members is a national priority. Furthermore, there is increased need for professionals with experience and interest in working with these brave individuals. Veterans and service members face significant challenges both during their service and after transitioning back to civilian settings. One such challenge for some veterans is substance use and its multidimensional effects on mental and physical health. The current article presents a brief but comprehensive overview of the prevalence and comorbidity of substance use disorders in veterans and service members. It also reviews practical information about assessment, treatment, and general clinical issues from the authors' clinical experience that is relevant to providers working with veterans and service members with substance use disorders. This information may be of particular interest to professionals with an interest in helping veterans, those who have limited experience working with veterans, or those who may work outside of standard military or Department of Veterans Affairs settings. Finally, future directions in this important area are discussed.