The TNSG is organized as a military reserve force whose members drill once per month unless called to active duty.

The Tennessee General Assembly authorized Governor Isham G. Harris to organize and equip a provisional force of volunteer state troops.

[8]: 31  During the Reconstruction Era, the Tennessee State Guard was used "to police elections, protect recently enfranchised freedmen, and thwart the operations of paramilitary groups such as the Ku Klux Klan.

[10] One famous Tennessean, Alvin York, belonged to the World War II-era Tennessee State Guard, accepting a commission as a colonel in 1941.

[14] In 2004, during the Iraq War, members of the Tennessee State Guard were activated to assist the 278th Armored Cavalry Regiment with pre-mobilization processing.

[15] In 2005, Governor Phil Bredesen activated the Tennessee State Guard to assist with relief efforts from Hurricane Katrina.

Aside from deploying to aid victims of Hurricane Katrina, and guarding military installations in the aftermath of the September 11 attacks, State Guardsmen, in preparing for their role as emergency response personnel, also participated in Operation Vigilant Guard in a disaster response drill organized as a mock earthquake disaster zone.

In 2014, at the request of the 194th Engineer Brigade of the Tennessee Army National Guard, several National Incident Management System (NIMS)-certified instructors from the 1st Regiment of the Tennessee State Guard provided NIMS training to members of the 194th Engineer Brigade over a two-day training period.

The State Guard plans to continue providing emergency management training to National Guardsmen based in other cities.

[20] In 2019, the 61st Medical Company (MEDCOM) participated in Operation Ardent/Shaken Fury, an eight state cooperative exercise responding to a large earthquake along the Mississippi River.

As part of the exercise, the 61st MEDCOM trained to triage, treat and transport disaster victims in coordination with other participating entities.

[21] Any able-bodied citizen with a high school diploma or GED, who is a resident of Tennessee, and has no criminal record is eligible for membership, although preference is given to honorably discharged members of all five branches from the United States military.

Civilians with specific professional skill sets, such as doctors, attorneys, chaplains or engineers, may be given preference for membership without prior military service.

[27] For formal events, including military funerals and award ceremonies, the Dress Blue or Army Service Uniform (ASU) is optional for Guardsmen.

Like National Guardsmen and federal reservists, state guard members receive protection from termination or other forms of discipline from their employers as a result of being called into active duty or drill status under Tennessee Code Annotated § 8-33-110.