Partnership Guide for Public Health Professionals

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Structure of the Department of Defense

The DoD has three military departments – the U.S. Army, U.S. Navy, and U.S. Air Force. The Army is organized within its own department. The Marine Corps and the Navy are organized under the Department of the Navy, and the Air Force and recently established Space Force are organized within the Department of the Air Force. The U.S. Coast Guard operates under the Department of Homeland Security unless the President activates them for war or another purpose. When activated, the Coast Guard operates under the Department of the Navy.

The three components of the military include active duty, National Guard, and Reserve. This distinction is important, as not all service members enter the military in the same way and each component has its own subculture within the greater culture of the military. Each branch of service has its own identity and language. Service members and veterans may appreciate being asked which branch of the military they serve(d) and what they do/did during their service.

Active Duty Component Forces

The United States Armed Forces are the military forces of the United States. The armed forces consist of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. Each of the different military services is assigned a role and domain. The U.S. Army conducts land operations, while the U.S. Navy and U.S. Marine Corps conduct maritime operations, with the Marine Corps specializing in amphibious and maritime shore operations in support of the Navy. The U.S. Air Force conducts air operations, while the U.S. Space Force conducts space operations. The U.S. Coast Guard is unique in that it is a military branch specializing in maritime operations and also a law enforcement agency.

To learn more about the active duty services, hover over the logos below.


The largest and oldest service in the U.S. military, the Army provides the ground forces that protect the United States. The Army is supported by two Reserve Forces – the Army Reserves and the Army National Guard – which can be tapped for trained personnel and equipment during times of need. The Reserves are "owned" and managed by the federal government, while each state "owns" its own National Guard. However, the President or the Secretary of Defense can "activate" state National Guard members into federal military service during times of need. Army personnel are referred to as Soldiers.

Marine Corps

The Marine Corps is often referred to as the "Infantry of the Navy" and they specialize in operations supported by naval ships. While amphibious operations are their primary specialty, in recent years, the Marine Corps has expanded to support other ground-combat operations. Like the Navy, there is no Marine Corps National Guard, but Marine Corps is supported in times of need by the Marine Corps Reserves. Marine Corps personnel are referred to as Marines.


The Navy's primary mission is to maintain the freedom of the seas. The Navy makes it possible for the United States to use the seas where and when our national interests require it. In addition, in times of conflict, the Navy transports Marines to specific areas of conflict and helps to supplement Air Force air power. In times of need, the Navy is supported by the Naval Reserves. Unlike the Army and Air Force, there is no Naval National Guard (although a few states have established "Naval Militias"). Navy personnel are commonly referred to as Sailors. Army personnel are referred to as Soldiers.

Coast Guard
"Coast Guardsman"

The Coast Guard is a military and a law enforcement service. In peacetime, the Coast Guard reports to the Department of Homeland Security and is primarily concerned with law enforcement, boating safety, sea rescue, and illegal immigration control. In times of conflict, the President can transfer part or all of the Coast Guard to the Department of the Navy and as such, it reports to the Navy. The Coast Guard is also supported by the Coast Guard Reserves and a volunteer Coast Guard Auxiliary in times of need. Coast Guard personnel are referred to as Coastguardsmen.

Air Force

The Air Force’s mission is to ensure American control of air, space, and cyberspace; provide air support to ground forces; and to transport personnel, equipment, and supplies worldwide. Like the Army, the active-duty Air Force is supplemented by the Air Force Reserves and the Air National Guard. Air Force personnel are referred to as Airmen.

Space Force

The Space Force is the youngest military service, established in 2020. Space Force was created to address the growing importance of space to both military operations and everyday life. They provide a centralized chain of command responsible for space-based systems such as GPS and intelligence satellites and conduct global space operations that enhance the way our joint and coalition forces fight. Personnel in the Space Force are referred to as Guardians.

Reserve Component Forces

The reserve components of the U.S. Armed Forces are military organizations whose members generally perform a minimum of 39 days of military duty per year and who augment the active duty (i.e., full-time) military when necessary.


The Army, Navy, Marines, Coast Guard, and Airforce all have reserve forces. The purpose of each reserve component is to provide trained units and qualified persons in times of war or national emergency and, at other times, when required to maintain national security.

Personnel in the Reserves are referred to the same as their active-duty counterparts:

Both reserve and National Guard units train, known as drill, one weekend a month plus two weeks a year for annual training, and must serve a certain number of hours each year to qualify for benefits and retirement. Many units perform training well beyond this minimum. After 9/11, the operations tempo (frequency of being called into active-duty status) for reserve and national guard units greatly increased.

The leadership and support services for reserve and National Guard units are full-time, active-duty personnel; however, most hold a civilian job full-time in addition to serving in their military role.

National Guard

Comprised of the Army National Guard and the Air National Guard, the National Guard is a versatile force, supporting combat missions, domestic emergencies, humanitarian efforts, homeland security operations, and more. Each state (including the District of Columbia) and U.S. territory has a National Guard unit that reports to their respective governor. The District of Columbia reports directly to the President. National Guard units can be activated for federal duty by the President and when they are, they report to the President.

In each state, the Army and Air National Guard share leadership at the top levels, known as Joint Force Headquarters (JFHQ). JFHQs are often part of a state agency for military affairs.

Army and Air National Guard personnel are referred to as Guardsmen.

State Defense Forces

Twenty-two states have additional state defense forces (SDF) that operate under the sole authority of the state. SDFs exist primarily to support and augment National Guard forces during domestic crises and to take its place should it be federalized and sent away to war. SDFs are called various names (Georgia State Defense Force, California State Guard, Indiana Guard Reserve, etc.). Locate your State Defense Force webpage.

SDF personnel (either work or volunteer) are referred to as Soldiers.

Structure of the Department of Veterans Affairs

Department-of-Veterans-Affairs-1024x683The Department of Veterans Affairs (VA is an agency of the federal government that provides benefits, healthcare, and cemetery services to military veterans. The Secretary of Veterans Affairs, a cabinet-level official, is appointed by the President. The VA is the federal government’s second largest department after the DoD; it operates independently from DoD, but the two organizations collaborate across several areas.

States, the District of Columbia, and U.S. Territories also operate state and territorial veteran’s affairs departments. While independent from VA, these departments are key partners in the mission to take care of veterans and their survivors.

State veteran’s agencies primarily assist veterans with accessing and applying for federal VA care and benefits. In addition to connecting veterans to federal resources, each state government offers additional services to their veterans such as tax exemptions and education benefits. Contact information for state and territorial veteran’s agencies is available on National Association of State Directors of Veteran’s Affairs search page.

Service Member and Family Demographics

The Military Lifecycle

Every fiscal year, DoD publishes a demographics report that provides a detailed overview of the military community – from active-duty and reserve members to their spouses and children. The report includes gender, race, age, education, family members, pay grades, installation populations, and other important facts.

Quick Stats as of 2022:

  • There are approximately 2.6 million service members including active-duty and reserve military personnel
  • 31% of active-duty members identify with racial minority groups, and 17.7% are Hispanic or Latino3
  • 82.7% identify as male and 17.3% identify as female (gender identity is not tracked by DoD)3
  • 60% were age 30 or younger3
  • Approximately 50% of service members are married and 35% had children3
  • Single parents make up about 6% of the force3
  • About 2% of personnel are in dual-military marriages, meaning both members of the couple are U.S. service members3
  • Approximately two-thirds of military personnel live off base4

3Department of Defense Demographics Profile (2021).

4 Else, D.H. (2001). Military Housing Privatization Initiative: Background and Issues. Report to Congress. Order code RL31039, July. Washington, DC: Congressional Research Service

The initial commitment for Miltary-Mud-Run--1024x683military personnel is eight years, but how this is broken up depends on the service branch military occupational specialty (i.e., job). The following summary by Swords to Plowshares outlines the military lifecycle and describes stressors and challenges associated with each phase of the lifecycle.

Service members usually spend four years on active duty and another four years in the reserves. Military personnel cede many of what we think of as fundamental rights of a U.S. citizen including freedom of speech or expression, freedom of assembly, and due process under the law. For example, although military personnel still have the right to vote and practice their religion, it is up to their military command as to when they may exercise those rights. In addition to the laws of the land, they are also governed by the Uniform Code of Military Justice and violators may be subject to non-judicial punishment, reduction in rank, reduced pay, and restricted nutrition intake for a specific amount time, as determined by command. In other words, the commitment is all encompassing and is generally made when the recruit is in their late teens.

Basic training is the acculturation phase of military life. Cadets leave behind their civilian identities and form new ones. Marines describe this as “losing the self” and “becoming part of the collective.” For some, they leave behind an unstable childhood and family dynamic; for many, they are leaving their family and civilian community for the first time. They learn their branch’s customs, social norms, policies, procedures (including how to wear the uniform, how to walk, talk, shower, eat), and rites and rituals. The physical demands are intense. The duration of Basic Training ranges from nine to thirteen weeks, depending on the branch, after which the next step is advanced training.
During advanced training, basic training is augmented with the specific training and education associated with their specific job, which a member of the armed forces will most likely perform throughout their military career. This is known as their Military Occupational Specialty (MOS).
A service member is assigned to a specific unit—in the U.S. or overseas—for the duration of their time in the military. The assignment can take as long as nine to ten months, starting from when they initially sign their enlistment paperwork with the recruiter.
Most units are an active deployable unit, meaning that they will be sent somewhere away from their home base. However, this does not necessarily mean they will be sent to engage in combat or even to a war zone. Deployments can be unpredictable and can be as long as fifteen months away from their base, home, and family. For those who are in the reserves or National Guard, this may also mean time away from their civilian work. For married or cohabitating personnel, this means that their spouse or partner will assume all responsibilities and duties that they normally share as a couple. Those who are single parents are required to assign custodial responsibility to another adult.
When they come to the end of their active service obligation (end of active obligated service, or EAOS), service members must decide if they want to re-enlist or leave the military. Upon exiting the military, service members receive discharge paperwork known as the DD-214, which they will use as proof of military service and includes their MOS, highest rank achieved, awards and medals, type of discharge (honorable, general, other than honorable, bad conduct or dishonorable), and reason for discharge. The DD-214 will be used to determine the VA benefits for which they are eligible and is even used when veterans secure government jobs. Because the narrative reason for their discharge is included in the document, this can stigmatize and put a permanent stamp on their experience in the military, especially for those who have been discharged for reasons related to Don’t Ask, Don’t Tell; sexual assault; or for punitive reasons that may or may not be connected to military-connected trauma. The process of exiting is variable depending on the branch of service as well as location. For some, there may be a Transition Assistance Program (TAP), which can be merely a checklist of information about returning to civilian life. The experience varies widely, with some military facilities, states, or localities offering more to prepare veterans to reintegrate into their communities, return or enroll in school, or resume employment.
If a service member decides to leave the military, it is called a “separation”. In the civilian world, one resigns, quits, retires, or moves on from a job; in the military, one separates from both a job and a culture. Exiting is rapid and there is often a 24-hour turnaround time from EOAS to separation. This can be shocking and stressful to the service member. In a short time, they have lost the support system cultivated over the years as well as their sense of purpose. Moreover, those who are stationed far from family or what used to be home may lack any connections or social resources; those exiting the military receive limited training on how to transition from the military to community life. As a result, veterans may be less prepared to secure housing and employment and re-acculturating to community norms.

Military Culture and Values

The United States military prides itself on values. Each of the services has their own set of values but all value of discipline, teamwork, self-sacrifice, loyalty, and fighting spirit. Key elements of military culture include:

  • Strict chain of command, routine, and structure
  • Emphasis on respect for authority and self
  • Image of strength and self-reliance
  • Commitment to honor and trustworthiness
  • Value of aggression and acting faster and harder

People choose to join the military for many reasons including family tradition, patriotism, training, leadership opportunities, education and housing benefits, and adventure.

Serving in the armed forces impacts individuals in numerous ways. The PsychArmor Institute surveyed hundreds of veterans about what they wanted civilians, employers, educators, health care providers, and therapists to know about them. Below are key messages obtained by the survey.

  • Remember that not all service members are “soldiers.” Each branch of the U.S. Military has their own mission, subculture, and terminology. Use terms such as “military personnel” or “veterans” as reference, and do not generalize all as “soldiers”.
  • The Reserves are part of the military. Reservists and National Guard members have unique challenges due to abrupt transitions between civilian life and military duty, which can be disruptive to work and family life. They often do not have similar resources and support as active-duty military personnel when they return from missions. Both reserves and active duty balance and complement each other.
  • Not everyone in the military is infantry. Jobs range from infantry to technicians, mechanics, cooks, administrators, lawyers, doctors, and musicians.
  • The military is always on duty. Readiness is a full-time, around the clock job and this takes a toll on military personnel and their families.
  • Not all service members have killed someone. Those who have do not want to talk about it. Do not question military personnel or veterans about this topic.
  • Not all military personnel have post-traumatic stress disorder. Post-traumatic stress disorder (PTSD) can be caused by many different types of trauma including combat. Most people who experience trauma do not go on to develop PTSD; the majority have naturally recovered and are doing fine.
  • It is hard for service members to ask for help. The military has a long-standing history of promoting emotional and physical perfection. Understanding that it is hard for service members to ask for help can help you serve them better.
  • Veterans differ in how much they identify with the military after they leave active duty. For example, some veterans who were not deployed in combat may not consider themselves veterans, although they are.
  • Military families serve alongside their service member. The military family’s experience is unique and challenging with frequent separation from loved ones. Some military families move every two or three years, making it difficult to establish school and employment. Military families are resilient, adaptive, and flexible.

For a deeper understanding of military life and stressors, read the National Academies of Sciences, Engineering, and Medicine’s report, Strengthening the Military Family Readiness System for a Changing American Society.

Where to Find Military Health Data

There are several open access data repositories that can offer insight on the health outcomes and behaviors of service members and veterans.

In addition to the publicly available sources outlined above, DoD routinely collects service member health data through periodic health assessments (PHA). PHAs include:

  • Self-reported health status
  • Measurement and documentation of vitals (height, weight, BP)
  • Vision screening
  • Medical conditions review with healthcare provider
  • Focused exam of identified conditions (as required)
  • Cardiovascular Screening Program Services (as required)
  • Recommendations for improvement of identified health conditions
  • Behavioral health screen
  • Laboratory Services (as required)
  • Immunizations (as required)

The service branches also collect their own health behavior data. One notable example is the Army’s Unit Risk Inventory (URI), which provides Soldiers the opportunity to give an honest, anonymous assessment of their well-being.

While PHA and URI data are not available to the public, it is important to understand that military leaders have access to robust sources of health data for their populations.

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