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Updated June 11, 2024
Defense Primer: Reserve Forces
The term reserve component (RC) refers collectively to the
ordered into federal service. When this happens, control
seven individual reserve components of the Armed Forces.
passes from the governor of the affected units and
Congress exercises authority over the reserve components
personnel to the President of the United States.
under its constitutional authority “to raise and support
Armies,” “to provide and maintain a Navy,” and “to
Reserve Categories
provide for organizing, arming, and disciplining the
All reservists, whether they are in the Reserves or the
Militia.” (Article I, Section 8)
National Guard, are assigned to one of three major reserve
categories: the Ready Reserve, the Standby Reserve, or the
There are seven reserve components:
Retired Reserve.
• Army National Guard
Ready Reserve
The Ready Reserve is the primary manpower pool of the
• Army Reserve
reserve components. Members of the Ready Reserve will
usually be called to active duty before members of the
• Navy Reserve
Standby Reserve or the Retired Reserve. The Ready
Reserve is made up of three subcomponents:
• Marine Corps Reserve
• The Selected Reserve contains those units and
• Air National Guard
individuals within the Ready Reserve designated as “so
essential to initial wartime missions that they have priority
• Air Force Reserve
over all other Reserves.” (DOD Instruction 1215.06.)
Members of the Selected Reserve are generally required to
• Coast Guard Reserve
perform one weekend of training each month and two
weeks of training each year, although some may train
The Space Force, under the Department of the Air Force,
more than this. When reservists are activated, they most
does not have a reserve component (10 U.S.C. §20001).
frequently come from this category.
The purpose of these seven reserve components, as codified
in law, is to “provide trained units and qualified persons
• The Individual Ready Reserve (IRR) is a manpower
available for active duty in the armed forces, in time of war
pool of individuals who have already received military
or national emergency, and at such other times as the
training, either in the Active Component or in the
national security may require, to fill the needs of the armed
Selected Reserve. They are not normally required to
forces whenever more units and persons are needed than are
perform training, but can be ordered to active duty under
in the regular components.” (10 U.S.C. §10102) The Army
certain circumstances.
National Guard and the Air National Guard also have an
important role under state authority, responding to various
• The Inactive National Guard (ING) is made up of
emergencies such as disasters and civil disorders.
those members of the Army National Guard who are in
an inactive status (currently there is no ING for the Air
Difference between Federal Reserves
National Guard). The ING is, for practical purposes, the
and National Guard
National Guard equivalent of the IRR.
The Army Reserve, Navy Reserve, Marine Corps Reserve,
Air Force Reserve, and Coast Guard Reserve are
There are just over one million members of the Ready
exclusively federal organizations. There are 54 separate
Reserve. This figure is broken down by service and
National Guard organizations: one for each state, and one
subcategory in Table 1.
each for Puerto Rico, Guam, the U.S. Virgin Islands, and
the District of Columbia. While the District of Columbia
Standby Reserve
National Guard is an exclusively federal organization and
The Standby Reserve contains those individuals who have a
operates under federal control at all times, the other 53
temporary disability or hardship and those who hold key
National Guards operate as state or territorial organizations
positions in their civilian jobs. They are not required to
most of the time. In this capacity, each of these
participate in military training and may only be ordered to
organizations is identified by its state or territorial name
active duty in limited circumstances.
(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
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Defense Primer: Reserve Forces
Table 1. Ready Reserve Personnel Strength
As of March 31, 2024
Individual Ready Reserve &
Reserve Component
Selected Reserve
Inactive National Guard
Total Ready Reserve
Army National Guard
323,270
1,724
324,994
Army Reserve
175,347
135,575
310,922
Navy Reserve
55,051
36,983
92,034
Marine Corps Reserve
32,493
56,922
89,415
Air National Guard
103,007
0
103,007
Air Force Reserve
65,787
31,523
97,310
Coast Guard Reserve
6,179
2,167
8,346
Total
761,134
264,894
1,026,028
Source: Defense Manpower Data Center.
Retired Reserve
In addition to activations under federal authority, members
The Retired Reserve includes Reserve personnel who are
of the National Guard can also be activated by their
receiving retired pay or who transfer into the Retired
governor for full time duty (i.e., state active duty) owing to
Reserve after qualifying for reserve retirement, but before
their unique state/federal status. They can also be activated
becoming eligible to receive retired pay. Members of the
under state control but with pay and benefits provided by
Retired Reserve may be ordered to active duty only in
the federal government. This is sometimes referred to as
limited circumstances.
Title 32 status in reference to the part of the United States
Code that governs this duty status.
Full-Time Support
Reserve units are primarily filled by traditional reservists:
Pay, Benefits, and Duty Status
members of the Selected Reserve who are usually required
Reservists’ pay and benefits may vary significantly based
to work one weekend a month and two weeks a year.
on the type of duty performed. Some key variables in
However, many reserve units are also staffed by one or
determining the compensation provided include (1) whether
more full-time civilian and/or military employees. These
an individual is performing active duty or inactive duty; (2)
employees, known as full-time support (FTS) personnel, are
if on active duty, the statutory authority under which the
“assigned to organize; administer; instruct; recruit and train;
individual is activated, the duration of the duty, and
maintain supplies, equipment and aircraft; and perform
whether the duty performed is in support of a contingency
other functions required on a daily basis in the execution of
operation; and (3) for the National Guard, whether the duty
operational missions and readiness preparations” (DOD
is in a state status or federal status.
Instruction 1205.18).
Activations
Relevant Statutes
There are four statutory provisions by which members of
Title 10, U.S. Code, Subtitle E (Reserve Components)
the National Guard and Reserve can be involuntarily
Title 32, U.S. Code (National Guard)
ordered to federal active duty for a year or more. Three of
these authorities have existed for decades, and are
commonly referred to as Full Mobilization (10 U.S.C.
§12301(a)), Partial Mobilization (10 U.S.C. §12302), and
CRS Products
Presidential Reserve Call-up (10 U.S.C. §12304). The
CRS Report RL30802, Reserve Component Personnel Issues:
fourth authority, added in 2011, allows reservists to be
Questions and Answers
activated to support the Combatant Commands for
preplanned missions (10 U.S.C. §12304b). These provisions
CRS Report R43808, Army Active Component (AC)/Reserve
differ from each other in terms of the statutory requirements
Component (RC) Force Mix: Considerations and Options for
for utilization, the number and category of reservists called
Congress
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
Kristy N. Kamarck, Coordinator, Specialist in Military
emergencies, for periods of up to 120 days (10 U.S.C.
Manpower
§12304a).
Carly A. Miller, Research Librarian
IF10540
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Defense Primer: Reserve Forces
Disclaimer
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