A variety of vertical and short take off and landing (VSTOL) concepts were investigated during the 1930s, 1940s, 1950s, and 1960s with lift engines embedded in the wings or fuselage. The aircraft had serious drawbacks, but contributed significantly to the development of the Harrier. The McDonnell Douglas AV-8B Harrier II is designed for combat air support, as well as combat air patrol, missions against ground defenses, and armed escort. Although the U.S. Marines are scheduled to retire their Harriers in 2012 when the F-35 enters service, it is expected that Harriers will still be operating with foreign air forces of the world for a number of years beyond 2012. Illustrated with line drawings and color profiles; 52 pages.