Post-traumatic stress disorder (PTSD) is a prevalent problem among military personnel and veterans. Identification of effective screening tools, diagnostic technologies, and treatments for PTSD is essential to ensure that all individuals in need of treatment are offered interventions with proven efficacy. Well-validated methods for screening and diagnosing PTSD are now available, and effective pharmacological and psychological treatments can be offered. Despite these advances, many military personnel and veterans do not receive evidence-based care. We review the literature on screening, diagnosis, and treatment of PTSD in military populations, and discuss the challenges to implementing the best evidence-based practices in clinical settings.