The Air Force Third Conference on Matrix Methods in Structural Mechanics, held at Wright-Patterson Air Force Base, Ohio on 19-21 October 1971, was sponsored jointly by the Air Force Flight Dynamics Laboratory, Air Force Institute of Technology, Air University. The purpose of the conference was to discuss the recent developments in the field of matrix methods of structural analysis and design of aerospace vehicles. The thirty-four papers presented were arranged into nine topic areas; design procedures, general methods, finite elements, dynamics, optimization, structural applications, computer graphics, non-linear effects, and non-structural applications. (Author).