Defense Primer: Reserve Forces

Updated February 19, 2026

Defense Primer: Reserve Forces

The term reserve component (RC) refers collectively to the

seven individual reserve components of the Armed Forces:

(1) the Army National Guard; (2) the Army Reserve; (3) the

Navy Reserve; (4) the Marine Corps Reserve; (5) the Air

National Guard (6) the Air Force Reserve; and (7) the Coast

Guard Reserve. The Space Force, under the Department of

the Air Force, does not have a reserve component (10

U.S.C. §20001).

The purpose of these seven reserve components, per 10

U.S.C. §10102, is to “provide trained units and qualified

persons available for active duty in the armed forces, in

time of war or national emergency, and at such other times

as the national security may require, to fill the needs of the

armed forces whenever more units and persons are needed

than are in the regular components.” The Army and Air

National Guards also have an important role under state

authority, responding to various emergencies such as

disasters and civil disorders.

Reserve Component Roles

Military policy describes the reserve components as an

“operational force,” elaborating that

The RCs provide operational capabilities and

strategic depth to meet U.S. defense requirements

across the full spectrum of conflict... In their

operational roles, RCs participate in a full range of

missions according to their Services’ force

generation plans. Units and individuals participate

in missions in an established cyclic or periodic

manner that provides predictability for the

combatant commands, the Services, Service

members, their families, and employers. In their

strategic roles, RC units and individuals train or are

available for missions in accordance with the

national defense strategy. As such, the RCs provide

strategic depth and are available to transition to

operational roles as needed.

The use of the RC increased after 1991. From 1986 to 1990,

the reserve components contributed approximately 3,000

person-years of active service. This increased to an annual

average of 35,000 person-years from 1996-2001. From

2002 to 2010 (including part of the conflicts in Iraq and

Afghanistan, along with domestic and foreign

counterterrorism actions), the RC contributed an annual

average of 146,000 person-years domestically and globally.

CRS has not found person-year figures for years after 2010.

Difference between Federal Reserves

and National Guard

The Army Reserve, Navy Reserve, Marine Corps Reserve,

Air Force Reserve, and Coast Guard Reserve are

exclusively federal organizations. There are 54 separate

National Guard organizations: one for each state, and one

each for Puerto Rico, Guam, the U.S. Virgin Islands, and

the District of Columbia (DC). While the DC National

Guard is an exclusively federal organization and operates

under federal control at all times, the other 53 National

Guards operate as state or territorial organizations most of

the time. In this capacity, each of these organizations is

identified by its state or territorial name (e.g., the California

National Guard or the Puerto Rico National Guard) and is

controlled by its respective governor. National Guard units

and personnel can be ordered into federal service. When

this happens, control of the affected units and personnel

passes from the state governor to the President of the

United States.

Reserve Categories

Ready Reserve

The Ready Reserve is the primary manpower pool of the

reserve components. Members of the Ready Reserve are

typically called to active duty before members of the

Standby Reserve or the Retired Reserve. The Ready

Reserve is made up of three subcomponents:

The Selected Reserve contains those units and individuals

within the Ready Reserve designated as “so essential to

initial wartime missions that they have priority over all

other Reserves.” (see Table 1).

Table 1. Selected Reserve Personnel Strength

Reserve Component

Selected

Reserve

Army National Guard

328,870

Army Reserve

169,519

Navy Reserve

58,165

Marine Corps Reserve

33,071

Air National Guard

105,120

Air Force Reserve

65,465

Total

760,210

Note: These figures reflect the number of personnel in each of the

reserve components as of September 30, 2025.

Source: Department of Defense, Defense Manpower Data

Center, Selected Reserve Personnel by Reserve Component and

Rank/Grade, September 2025.

Members of the Selected Reserve are generally required to

perform one weekend of training each month and two

weeks of training each year, although some may train more

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Defense Primer: Reserve Forces

than this. When reservists are activated, they most

frequently come from this category.

Title 32 status in reference to the part of the United States

Code that governs this duty status.

The Individual Ready Reserve (IRR) is a manpower pool

of individuals who have already received military training,

either in the Active Component or in the Selected Reserve.

They are not normally required to perform training, but can

be ordered to active duty under certain circumstances. The

Inactive National Guard (ING) is, for practical purposes,

the National Guard equivalent of the IRR. There is

currently no ING for the Air National Guard.

Pay, Benefits, and Duty Status

Standby Reserve

The Standby Reserve contains those individuals who have a

temporary disability or hardship and those who hold key

positions in their civilian jobs. They are not required to

participate in military training and may only be ordered to

active duty in limited circumstances.

Retired Reserve

The Retired Reserve includes Reserve personnel who are

qualified for reserve retirement. Members of the Retired

Reserve may be ordered to active duty only in limited

circumstances.

Full-Time Support

Reserve units are primarily filled by traditional reservists:

members of the Selected Reserve who are usually required

to work one weekend a month and two weeks a year.

However, many reserve units are also staffed by one or

more full-time civilian and/or military employees. These

employees, known as full-time support (FTS) personnel, are

“assigned to organize; administer; instruct; recruit and train;

maintain supplies, equipment, and aircraft; and perform

other functions required on a daily basis in the execution of

operational missions and readiness preparation.” (DOD

Instruction 1205.18)

Activations

Reservists’ pay and benefits may vary significantly based

on the type of duty performed. Some key variables in

determining the compensation provided include (1) whether

an individual is performing active duty or inactive duty;

(2) if on active duty, the statutory authority under which the

individual is activated, the duration of the duty, and

whether the duty performed is in support of a contingency

operation; and (3) for the National Guard, whether the duty

is in a state status or federal status.

Issues for Congress

• Congress may consider whether the reserves’ structure,

resourcing, doctrines, and legislative authorities enable

them to fulfil both operational and strategic roles.

Congress might also consider how the balance of

capabilities between the RC and the active component

underpins those roles.

• Congress may consider changes to the RC duty status

system, such as those proposed in an August 2025

RAND Corporation report and the Duty Status Reform

Act (H.R. 6976).

• Congress may consider the role of the reserve

components (and the Armed Forces in general) in

domestic security activities.

• Congress may assess the RC’s operational and personnel

tempo (OPTEMPO and PERSTEMPO) in both federal

and state mobilizations and the potential impact on

servicemember wellbeing and readiness.

• Congress may consider whether RC pay and benefits are

adequate to meet recruiting and retention targets.

There are four statutory provisions by which members of

the National Guard and Reserve can be involuntarily

ordered to federal active duty for a year or more.

These are commonly referred to as Full Mobilization (10

U.S.C. §12301(a)), Partial Mobilization (10 U.S.C.

§12302), and Presidential Reserve Call-up (10 U.S.C.

§12304), and activation in support of pre-planned missions

for the Combatant Commands (10 U.S.C. §12304b). These

provisions differ from each other in terms of the statutory

requirements for utilization, the number and category of

reservists authorized for call up, and the duration of the call

up. Another authority added in 2011, provides for

involuntarily activating members of the Army Reserve,

Navy Reserve, Marine Corps Reserve, and Air Force

Reserve to respond to major disasters or emergencies, for

periods of up to 120 days (10 U.S.C. §12304a).

In addition to activations under federal authority, members

of the National Guard can also be activated by their

governors for full-time duty (i.e., state active duty) owing to

their unique state/federal status. They can also be activated

under state control but with pay and benefits provided by

the federal government. This is sometimes referred to as

Relevant Statutes

Title 10, U.S. Code, Subtitle E (Reserve Components)

Title 32, U.S. Code (National Guard)

CRS Products

CRS Report RL30802, Reserve Component Personnel Issues:

Questions and Answers

CRS Report R43808, Army Active Component (AC)/Reserve

Component (RC) Force Mix: Considerations and Options for

Congress

Nicholas M. Munves, Analyst in U.S. Defense Policy

Carly A. Miller, Senior Research Librarian

Ebrima M'Bai, U.S. Army Fellow

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Defense Primer: Reserve Forces

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