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Updated December 12, 2018
Defense Primer: Reserve Forces
The term reserve component (RC) refers collectively to the
Reserve Categories
seven individual reserve components of the Armed Forces.
All reservists, whether they are in the Reserves or the
Congress exercises authority over the reserve components
National Guard, are assigned to one of three major reserve
under its constitutional authority “to raise and support
categories: the Ready Reserve, the Standby Reserve, or the
Armies,” “to provide and maintain a Navy,” and “to
Retired Reserve.
provide for organizing, arming, and disciplining the
Militia....” (Article I, Section 8)
Ready Reserve
The Ready Reserve is the primary manpower pool of the
There are seven reserve components:
reserve components. Members of the Ready Reserve will
usually be called to active duty before members of the
Army National Guard
Standby Reserve or the Retired Reserve. The Ready
Reserve is made up of three subcomponents:
Army Reserve
The Selected Reserve contains those units and
Navy Reserve
individuals within the Ready Reserve designated as “so
essential to initial wartime missions that they have
Marine Corps Reserve
priority over all other Reserves.” (DOD Instruction
1215.06.) Members of the Selected Reserve are
Air National Guard
generally required to perform one weekend of training
each month and two weeks of training each year,
Air Force Reserve
although some may train more than this. When
reservists are activated, they most frequently come from
Coast Guard Reserve
this category.
The purpose of these seven reserve components, as codified
The Individual Ready Reserve (IRR) is a manpower
in law, is to “provide trained units and qualified persons
pool of individuals who have already received military
available for active duty in the armed forces, in time of war
training, either in the Active Component or in the
or national emergency, and at such other times as the
Selected Reserve. They are not normally required to
national security may require, to fill the needs of the armed
perform training, but can be ordered to active duty under
forces whenever more units and persons are needed than are
certain circumstances.
in the regular components.” (10 U.S.C. 10102) The Army
National Guard and the Air National Guard also have an
The Inactive National Guard (ING) is made up of
important role under state authority, responding to various
those members of the Army National Guard who are in
emergencies such as disasters and civil disorders.
an inactive status (currently there is no ING for the Air
National Guard). The ING is, for practical purposes, the
Difference Between Federal Reserves
National Guard equivalent of the IRR.
and National Guard
The Army Reserve, Navy Reserve, Marine Corps Reserve,
There are more than 1 million members of the Ready
Air Force Reserve, and Coast Guard Reserve are
Reserve. This figure is broken down by service and
exclusively federal organizations. There are 54 separate
subcategory in Table 1.
National Guard organizations: one for each state, and one
for Puerto Rico, Guam, the U.S. Virgin Islands, and the
Standby Reserve
District of Columbia. While the District of Columbia
The Standby Reserve contains those individuals who have a
National Guard is an exclusively federal organization and
temporary disability or hardship and those who hold key
operates under federal control at all times, the other 53
defense-related positions in their civilian jobs. They are not
National Guards operate as state or territorial organizations
required to participate in military training and may only be
most of the time. In this capacity, each of these
ordered to active duty in limited circumstances. There are
organizations is identified by its state or territorial name
approximately 11,400 members of the Standby Reserve.
(e.g., the California National Guard or the Puerto Rico
National Guard) and is controlled by its respective
Retired Reserve
governor. National Guard units and personnel can be
The Retired Reserve includes Reserve personnel who are
ordered into federal service. When this happens, control
receiving retired pay or who transfer into the Retired
passes from the governor of the affected units and
Reserve after qualifying for reserve retirement, but before
personnel to the President of the United States.
becoming eligible to receive retired pay. Members of the
Retired Reserve may be ordered to active duty only in
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Defense Primer: Reserve Forces
Table 1. Ready Reserve Personnel Strength
As of September 30, 2018
Individual Ready Reserve &
Ready Reserve
Reserve Component
Selected Reserve
Inactive National Guard
Total
Army National Guard
335,204
1,184
336,388
Army Reserve
188,811
99,914
288,725
Navy Reserve
58,196
41,236
99,432
Marine Corps Reserve
38,333
64,159
102,492
Air National Guard
107,469
0
107,469
Air Force Reserve
68,703
28,394
97,097
Coast Guard Reserve
6,126
1,579
7,705
Total
802,842
236,466
1,039,308
Source: Official Guard and Reserve Manpower Strengths and Statistics, September 2018.
limited circumstances. There are about 780,000 members of
their unique state/federal status. They can also be activated
the Retired Reserve.
under state control but with pay and benefits provided by
the federal government. This is sometimes referred to as
Full-Time Support
Title 32 status in reference to the part of the United States
Reserve units are primarily filled by traditional reservists:
Code that governs this duty status.
members of the Selected Reserve who are usually required
to work one weekend a month and two weeks a year.
Pay, Benefits, and Duty Status
However, many reserve units are also staffed by one or
Reservists’ pay and benefits may vary significantly based
more full-time civilian and/or military employees. These
on the type of duty performed. Some key variables in
employees, known as full-time support (FTS) personnel, are
determining the compensation provided include (1) whether
“assigned to organize; administer; instruct; recruit and train;
an individual is performing active duty or inactive duty; (2)
maintain supplies, equipment and aircraft; and perform
if on active duty, the statutory authority under which the
other functions required on a daily basis in the execution of
individual is activated, the duration of the duty, and
operational missions and readiness preparations....”(DOD
whether the duty performed is in support of a contingency
Instruction 1205.18).
operation; and (3) for the National Guard, whether the duty
is in a state status or federal status.
Activations
At present, there are four statutory provisions by which
Relevant Statutes
members of the National Guard and Reserve can be
involuntarily ordered to federal active duty for a year or
Title 10, U.S. Code, Subtitle E (Reserve Components)
more. Three of these authorities have existed for decades,
Title 32, U.S. Code (National Guard)
and are commonly referred to as Full Mobilization (10 USC
12301(a)), Partial Mobilization (10 U.S.C. 12302), and
Presidential Reserve Call-up (10 U.S.C. 12304). The fourth
authority, added in 2011, allows reservists to be activated to
CRS Products
support the Combatant Commands for preplanned missions
CRS Report RL30802, Reserve Component Personnel Issues:
(10 U.S.C. 12304b). These provisions differ from each
Questions and Answers, by Lawrence Kapp and Barbara Salazar
other in terms of the statutory requirements for utilization,
Torreon
the number and category of reservists called up, and the
duration of the call up. Another authority added in 2011
CRS Report R43808, Army Active Component (AC)/Reserve
provides for involuntarily activating members of the Army
Component (RC) Force Mix: Considerations and Options for
Reserve, Navy Reserve, Marine Corps Reserve, and Air
Congress, by Andrew Feickert and Lawrence Kapp
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
Lawrence Kapp, Specialist in Military Manpower Policy
of the National Guard can also be activated by their
governor for full time duty (i.e., state active duty) owing to
IF10540
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Defense Primer: Reserve Forces
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