The Army Reserve is comprised of three groups of Soldiers: the Selected Reserve (SR), the Individual Ready Reserve (IRR) and the Retired Reserve (RR). In total, there are more than one million Army Reserve Soldiers ready to serve the nation when called upon by the President.
The Army Reserve is actively engaged in Operations Iraqi Freedom, Enduring Freedom and Noble Eagle.
The Selected Reserve is the most readily available group of Army Reserve Soldiers to the President. The Selected Reserve is comprised of Troop Program Units (TPUs), Active Guard and Reserve (AGR) Soldiers and Individual Mobilization Augmentees (IMAs). In the event of an emergency, all members of the Selected Reserve and up to 30,000 members of the Individual Ready Reserve (IRR) can be mobilized.
The Army Reserve is authorized to have more than 185,000 Soldiers in more than 6,000 Troop Program Units (TPU). These men and women typically train on selected weekends and perform annual training.
AGR Soldiers serve full time in units and organizations of the Army Reserve or that directly support the Army Reserve.
The Army Reserve's IMAs are assigned to high-level headquarters where they would serve if mobilized. Most IMAs train annually for two weeks.
DIMA positions are critical elements for mobilization during Presidential Reserve Call-up (PRC), and require an even higher level of proficiency than IMA Soldiers. Soldiers assigned to these positions train at least 24 days throughout a year, plus a 2-week annual training.
Members of the Individual Ready Reserve (IRR) are trained Soldiers who may be called upon, if needed, to replace Soldiers in Active and Army Reserve units. Many of the Soldiers in the IRR have left Army recently and still have military commitment. Others have chosen to remain as Army Reserve Soldiers, but not as a unit member or IMA. In all, there are about 163,000 members of the IRR.
The Retired Reserve consists of approximately 715,000 retirees from the Army (Active Army, Army Reserve and Army National Guard) who remain part of the Army Reserve family.