Air Transport Services Group (ATSG) is an American aviation holding company which provides air cargo transportation and related services to air carriers and other companies that outsource their air cargo lift requirements. ATSG subsidiaries include three cargo airlines with separate and distinct U.S. FAA Part 121 Air Carrier certificates. ATSG provides air cargo lift, aircraft leasing, aircraft maintenance services, airport ground services, fuel management, specialized transportation management, and air charter brokerage services.

ATSG owns a 25 percent equity interest in West Atlantic.

In March 2016, ATSG announced an agreement to operate an air cargo network to serve Amazon.com customers in the United States including: the leasing of 20 Boeing 767 freighter aircraft by ATSG subsidiary Cargo Aircraft Management; the operation of the aircraft by ATSG airline, Air Transport International; and gateway and logistics services provided by LGSTX Services. The 20 leases will be for five to seven years and operations agreements are for five years. ATSG will also granted Amazon warrants to soon buy 9.99% and up to 19.9% over a five-year period of ATSG common shares.

In January 2017, ATSG announced it had acquired Tampa, Florida-based PEMCO World Air Services.