On 13 December 1919, the United States House of Representatives passed an appropriations bill for $9.6 million for the purchase of additional land at military camps "which are to be made part of the permanent military establishment."
Brooks Field was allocated $140,446 of this amount.

In May 1919, the pilot instructor school was closed and a Balloon and Airship School was opened for pilots and ground crew members.
A huge 91,000-square-foot airship hangar was constructed.

Balloon units assigned
67th Balloon Company, May–June 1919
72d Balloon Company, May–June 1919
93d to 99th Balloon Company, May–June 1919
Consolidated into the Air Corps Balloon and Airship School, Brooks Field, June 1919
However, a series of mishaps in operating the hydrogen-filled craft led to the transfer of the school from Brooks to Scott Field, Illinois on June 26, 1922.
 The base commander at the time, Major John A. Paegelow, an experienced commander in lighter-than-air craft activities, left for the position of executive officer at Scott Field the same year.
 After the cancellation of the airship training, the 11th School Group was formed at Brooks Field as the Primary Flying School for the Air Service and Army Air Corps, replacing the World War I school at Carlstrom Field, Florida.

 
The Primary Flying School operated between September 1922 through July 1931.
The school took about six months initially, with advanced training later divided into three months each of basic and advanced instruction.
The dual trainer initially used was the Curtiss JN-6H. Brooks later accepted other planes, including Vought VE-7 Bluebirds and Dayton-Wright TA-3s, for evaluation, but JNs were used until 1926.
The beginning class in March of that year was the first without Jennies.
Students now flew in the new Consolidated PT-1, with tandem seats and a Wright E engine.
A few National Guard officers went to Brooks Field in January 1923 for pilot instruction.
World War I flyers underwent refresher training while others took the regular course.
Eight of the ten officers entering graduated to become junior airplane pilots.
The Air Service suggested, and the Militia Bureau adopted, a policy of giving men flying training before commissioning them in the Guard.
During the 1920s, the Primary Flying School at Brooks expanded but still could not accommodate all primary students.
Needing another school, the Air Corps reopened March Field, California.

Reorganizing pilot training, the Air Corps created a Training Center at San Antonio with Brig.
Gen. Frank P. Lahm in charge.
He opened headquarters at Duncan Field on September 1, 1926.
As an Assistant Chief
of Air Corps, he commanded the Primary Flying School and the School of Aviation Medicine (Flight Surgeons) at Brooks Field, and the Advanced Flying School at Kelly Field.
In 1927 basic moved out of the advanced phase and combined with primary.
At that point, primary-basic changed to eight months in length and advanced to four months.
With the beginning of the five-year expansion program.
More than 1,400 pilots were trained during those years and graduates included such notable aviation figures as Generals Claire L. Chennault, Thomas D. White, Nathan F. Twining, and Col.
Charles A. Lindbergh.

Also during this period, the School of Aviation Medicine was moved from Mitchel Field, New York, to Brooks.
The flying school was a source for aviation medicine research and, in turn, the School of Aviation Medicine provided a means to screen, examine and upgrade the caliber of cadets being trained at Brooks.
Both organizations were transferred to the newly constructed Randolph Field in October 1931.

On September 28, 1929, Brooks was the site for the first successful mass parachute drop in the world.
The concept, conceived and implemented at Brooks, confirmed the practicality of tactical paratrooper warfare.
The concept proved its value during World War II.

During the 1930s, Brooks was the center of aerial observation activity and several units were trained in tactical observation.
In 1938, the Air Corps wanted to move Headquarters 21st Balloon
On 13 December 1919, the United States House of Representatives passed an appropriations bill for $9.6 million for the purchase of additional land at military camps "which are to be made part of the permanent military establishment." Brooks Field was allocated $140,446 of this amount.
In May 1919, the pilot instructor school was closed and a Balloon and Airship School was opened for pilots and ground crew members. A huge 91,000-square-foot airship hangar was constructed.
Balloon units assigned
67th Balloon Company, May–June 1919
72d Balloon Company, May–June 1919
93d to 99th Balloon Company, May–June 1919
Consolidated into the Air Corps Balloon and Airship School, Brooks Field, June 1919
However, a series of mishaps in operating the hydrogen-filled craft led to the transfer of the school from Brooks to Scott Field, Illinois on June 26, 1922.  The base commander at the time, Major John A. Paegelow, an experienced commander in lighter-than-air craft activities, left for the position of executive officer at Scott Field the same year.  After the cancellation of the airship training, the 11th School Group was formed at Brooks Field as the Primary Flying School for the Air Service and Army Air Corps, replacing the World War I school at Carlstrom Field, Florida.
 
The Primary Flying School operated between September 1922 through July 1931. The school took about six months initially, with advanced training later divided into three months each of basic and advanced instruction. The dual trainer initially used was the Curtiss JN-6H. Brooks later accepted other planes, including Vought VE-7 Bluebirds and Dayton-Wright TA-3s, for evaluation, but JNs were used until 1926. The beginning class in March of that year was the first without Jennies. Students now flew in the new Consolidated PT-1, with tandem seats and a Wright E engine. A few National Guard officers went to Brooks Field in January 1923 for pilot instruction. World War I flyers underwent refresher training while others took the regular course. Eight of the ten officers entering graduated to become junior airplane pilots. The Air Service suggested, and the Militia Bureau adopted, a policy of giving men flying training before commissioning them in the Guard. During the 1920s, the Primary Flying School at Brooks expanded but still could not accommodate all primary students. Needing another school, the Air Corps reopened March Field, California.
Reorganizing pilot training, the Air Corps created a Training Center at San Antonio with Brig. Gen. Frank P. Lahm in charge. He opened headquarters at Duncan Field on September 1, 1926. As an Assistant Chief
of Air Corps, he commanded the Primary Flying School and the School of Aviation Medicine (Flight Surgeons) at Brooks Field, and the Advanced Flying School at Kelly Field. In 1927 basic moved out of the advanced phase and combined with primary. At that point, primary-basic changed to eight months in length and advanced to four months. With the beginning of the five-year expansion program. More than 1,400 pilots were trained during those years and graduates included such notable aviation figures as Generals Claire L. Chennault, Thomas D. White, Nathan F. Twining, and Col. Charles A. Lindbergh.
Also during this period, the School of Aviation Medicine was moved from Mitchel Field, New York, to Brooks. The flying school was a source for aviation medicine research and, in turn, the School of Aviation Medicine provided a means to screen, examine and upgrade the caliber of cadets being trained at Brooks. Both organizations were transferred to the newly constructed Randolph Field in October 1931.
On September 28, 1929, Brooks was the site for the first successful mass parachute drop in the world. The concept, conceived and implemented at Brooks, confirmed the practicality of tactical paratrooper warfare. The concept proved its value during World War II.
During the 1930s, Brooks was the center of aerial observation activity and several units were trained in tactical observation. In 1938, the Air Corps wanted to move Headquarters 21st Balloon 
Brooks Air Force Base