This study traces the development of close air support tactics and operations in South Vietnam from 1961 through 1973. The early years (1961-64) witnessed the buildup of Farm Gate operations and introduction of the Tactical Air Control System (Barn Door). Tactics evolved for the 0-1 Bird Dog FAC and for such strike aircraft as the T-28 Trojan, B-26 Invader, and A-lE Skyraider. Ordnance problems were tackled and headway made. During the buildup (1965-68) the 0-2A Skymaster and OV-10 Bronco bolstered forward air control. Strike operations were strengthened by the F-100 Super Sabre, B-57 Canberra, F-4 Phantom, F-5 Freedom Fighter, and A-37 Dragonfly. Gunships (the AC-47 Spooky, AC-130 Spectre, AC-119G Shadow, and AC-119K Stinger) also gave excellent assistance to group troops. Support of Special Forces commenced. Inroads were made on problems of coordination, command, and control of tactical air power. Tactics were further refined to meet the changing needs of close air support. In the final period (1969-73) the OV-10 acted as an armed FAC. The A-7 Corsair II entered the war. In 1973 the pullout of American troops began. Lastly, the study discusses the A-10 close air support aircraft.