Military members, veterans, and their families belong to a unique American subculture. Studies have identified the need for mental health professionals to attain military cultural competency to practice more effectively within this subculture. As an 88-year-old counseling and training agency with a record of service to the military/veteran communities, it was appropriate that Council for Relationships commit to providing training in military culture for its therapists and students. From 2017 to 2019, the course highlighted in this paper was part of an approved Institutional Review Board (IRB) study intended to assess the success of graduate-level instructional activities focused on promoting participants’ military and veteran-related cultural competency. This article includes an evaluation of the 2013–14 four-day training on military culture that preceded the course. In both, the unique cultural factors associated with military and veteran service were addressed within the context of evidence-based behavioral health treatment. A survey of the four-day participant training and qualitative interview follow-ups revealed that information about the military and its impact on veterans and families promoted changes in attitudes, knowledge, and clinical practice for both experienced and newly trained clinicians. These findings were replicated in the three-year evaluation results. This assessment provides valuable insight about military culture training for practicing and future mental health clinicians. Since there is very little information available in the literature on successful military culture competency training, sharing these results with the broader military and academic communities will give others information on the important components of effective training programs for clinicians, thus, potentially improving therapeutic services to these populations.