309th

309th may refer to:


 * 309th Aerospace Maintenance and Regeneration Group, a United States Air Force storage and maintenance facility in Tucson, Arizona
 * 309th Air Division, inactive United States Air Force organization
 * 309th Airlift Squadron, part of the 86th Airlift Wing at Chièvres Air Base, Belgium
 * 309th Bombardment Squadron or 525th Fighter Squadron, United States Air Force unit
 * 309th Fighter Squadron (309 FS), part of the 56th Operations Group at Luke Air Force Base, Arizona
 * 309th Maintenance Wing, inactive wing of the United States Air Force last based at Hill Air Force Base, Utah
 * 309th Military Intelligence Battalion (United States) conducts initial entry, collective, and functional training
 * 309th Rifle Division (Soviet Union), formed for the first time as a standard Red Army rifle division shortly after the German invasion