The company's military-related activities are centred on the design, manufacture, and support of fighter aircraft, bombers, transports, helicopters, and missiles. Its products include, among others, the F-15 Eagle, F/A-18 Hornet and Super Hornet, and AV-8 Harrierfighters; the C-17 Globemaster III airlifter; the AH-64 Apache series of attack helicopters; the CH-47 Chinook transport helicopter; and the AWACS (Airborne Warning and Control System) aircraft, based on the 767. Boeing contributes to the Lockheed Martin (Lockheed Martin Corporation) F-22 Raptor air-superiority stealth fighter and the Northrop Grumman (Northrop Grumman Corporation) B-2 Spirit stealth bomber. In partnership with Bell Helicopter Textron (Textron Inc.), it builds the V-22 Osprey tilt-rotor aircraft, and, with United Technologies (United Technologies Corporation)' Sikorsky division, it makes the RAH-66 Comanche armed reconnaissance helicopter. The company also builds the Harpoon antiship missile, the air-launched Standoff Land Attack Missile (SLAM), and the air-launched cruise missile (ALCM).

In the space and communications sector, Boeing produces the Delta family of launch vehicles; the Inertial Upper Stage (IUS), an in-space solid-rocket booster; and rocket engines for Delta launchers and other vehicles. It participates in processing, ground operation, and training activities for the U.S. space shuttle fleet through United Space Alliance, a joint venture with Lockheed Martin Corporation. As the National Aeronautics and Space Administration's (NASA's) prime contractor for the International Space Station (ISS), Boeing leads an industry team comprising most major U.S. aerospace companies and hundreds of smaller suppliers and integrates the work of ISS participants from non-U.S. countries. Its involvement in commercial space development includes partnerships in the multinational Sea Launch Company and in the Teledesic consortium formed to build a satellite-based, Internet-like telecommunications service. It also makes satellites for the Navstar Global Positioning System (GPS). In 2000 Boeing employed a workforce of about 200,000 people in 60 countries and 27 U.S. states.

Boeing's origin dates to 1916 when the American timber merchant William E. Boeing founded Aero Products Company shortly after he and U.S. Navy officer Conrad Westervelt developed a single-engine, two-seat seaplane, the B&W. Renamed Boeing Airplane Company in 1917, the enterprise built “flying boats” for the Navy during World War I, and in the 1920s and '30s it successfully sold its trainers, pursuit planes, observation craft, torpedo planes, and patrol bombers to the U.S. military. In the late 1920s Boeing Airplane expanded into airmail services, and in 1928 William Boeing formed Boeing Airplane & Transport Corporation to encompass both manufacturing and airline operations. The next year the company was renamed United Aircraft and Transport Corporation and acquired several aircraft makers, among them Chance Vought, Avion (which became Northrop Aircraft), Stearman Aircraft, Sikorsky Aviation, engine manufacturer Pratt & Whitney, and aircraft and propeller maker Hamilton Metalplane. In 1931 it combined four smaller airlines under its ownership into United Airlines. In 1934, under new U.S. antitrust legislation (the Air Mail Act of 1934), aircraft manufacture was required to be divorced from air transport, and a newly incorporated Boeing Airplane Company became one of the three companies to emerge from the dissolution of United Aircraft and Transport. The other two were United Aircraft Corporation (now United Technologies Corporation) and United Airlines.

In the space sector during the 1960s and '70s, Boeing built the Lunar Orbiters (Lunar Orbiter), NASA's first spacecraft to orbit the Moon (1966–67), and the Mariner 10 space probe, which took the first close-up pictures of the surface of Mercury (1974–75). It also designed and built the first stage of the Saturn V rockets that sent Apollo (Apollo program) astronauts to the Moon and the battery-powered Lunar Roving Vehicles used in the Apollo 15, 16, and 17 missions. In 1976 it entered the upper-stage-rocket arena when it was selected to develop the Inertial Upper Stage (IUS), a two-stage payload delivery vehicle that can be taken into space by either a space shuttle or a launcher such as the Titan (Titan rocket). In 1993 NASA selected Boeing as the prime contractor for the ISS (International Space Station), and two years later the company became responsible for the integration and verification of ISS systems and the design, analysis, manufacture, verification, and delivery of the American components of the station.

The history of Rockwell International's aerospace and defense business dates to the founding in 1928 of North American Aviation, Incorporated, by the financier and corporate organizer Clement Melville Keys as an elaborate holding company, 70 percent of which was owned by Curtiss Aeroplane & Motor Corporation and the remainder by Transcontinental Air Transport (TAT), Curtiss Flying Service, and Donald Douglas (Douglas, Donald). In 1933 automobile giant General Motors (General Motors Corporation) (GM) acquired a 30 percent stake in North American Aviation through its subsidiary General Aviation Corporation, which also owned Fokker Aircraft. By early 1934 North American owned the Sperry Gyroscope Company, more than a quarter of its former parent TAT (which later would become Trans World Airlines (Trans World Airlines, Inc.)), and a majority share of Western Air Express. Because of the new U.S. antitrust legislation separating aircraft manufacturers from airlines, GM sold most of its holdings in aviation. Although North American Aviation remained partially owned by GM, it became an autonomous company. Under the leadership of the aircraft engineer James Kindelberger, who became North American's president in 1934, the company transformed itself from a holding company into a highly successful aircraft manufacturer by focusing on single-engine airplanes, and over the next three decades it built more military airplanes than any other American manufacturer. Between 1935 and 1945 North American supplied more than 42,000 military aircraft, which included the distinguished P-51 Mustang fighter and the T-6 Texan trainer (both first flown in 1940).

After World War II, North American's aircraft division developed the F-86 Sabre (first flown in 1949), the first American swept-wing jet fighter, and the F-100 Super Sabre (F-100), the first American production fighter to fly at supersonic speeds for sustained periods. GM sold its controlling share of North American to the public in 1948, after which the aircraft maker began to diversify, becoming involved in the development of rockets, guidance systems, and atomic energy. In the 1950s it built the X-15 rocket-powered research aircraft for the U.S. military and NASA in order to gather information on flight conditions beyond the atmosphere. First flown in 1959, the X-15 set separate unofficial altitude and speed records for aircraft during the 1960s—almost 108 km (67 miles) and 6.7 times the speed of sound. In 1967 North American Aviation merged with the much smaller company Rockwell Standard Corporation, a maker of automotive parts and later of aircraft, to form North American Rockwell Corporation, which was renamed Rockwell International Corporation in 1973. Rockwell International's last airplane was the supersonic, variable-wing B-1B (B-1) Lancer bomber (first flown in 1984), but it remained a major subcontractor to the commercial aerospace sector.

McDonnell Aircraft was founded in 1939 by the American aeronautical engineer James Smith McDonnell. Although the company struggled during its first year, it soon grew rapidly as a manufacturer of airplane parts. Because of the company's research on the use of jet propulsion for aircraft, the U.S. Navy awarded it a contract to build the FH-1 Phantom, which, in 1946, became the first jet aircraft used on an aircraft carrier. With the success of its highly versatile F-4 Phantom II fighter (first flown in 1958) supplied to the U.S. Air Force and Navy, McDonnell grew quickly to became a major defense supplier. During the 1960s it built the first series of American manned spacecraft—the Mercury and Gemini space capsules.