Although there are many definitions of military social work, this article primarily focuses on social work by uniformed personnel within the United States military. Social work with military and veteran-connected populations is also done by civilian professionals. The history of military social work in the United States is rooted in the civilian professional social work community and is a microcosm of that sector. Military social work has a rich history of providing services to military men and women and their families during periods of peace, conflict, and national crises. Military social workers have been involved in humanitarian operations and have participated in multinational peace-keeping operations. Social work in the Army, Navy, and Air Force is tailored to the mission of their particular service. However, joint operations between the services are becoming more frequent. Military social workers adhere to the National Association of Social Workers (NASW) code of ethics while providing service to an institution with its own unique culture, standards, and values. The role of military social workers has expanded since the Global War on Terrorism began, in 2001. Military social work encompasses a wide variety of skills, performed by social workers who are both civilian and military, ranging from crisis to working with families. Military social work is unique and often faces ethical dilemmas even though military social workers still follow the National Association of Social Workers’ Code of Ethics. The history of military social work dates back to the early 1940s, but has evolved with the needs of military members and their families. The Army, Air Force, and Navy all have social workers, both civilian and those who wear the uniform. Due to the number of veterans and military families living throughout the United States, and seeking care in community settings, recommendations to establish competencies for social workers working with military and veteran-connected populations is underway.