Abstract This is a comprehensive treatment covering the development of turbosuperchargers, which today are making possible the outstanding performance at high altitudes of United States military aircraft. The basic function of supercharging is to increase the intake-manifold air pressure in an engine, as a result of which the primary objectives are attained of (a) maintaining full (rated) power at altitude; (b) increasing power at sea level; (c) improving fuel economy for cruising. Fundamental design considerations cover the means for accomplishing these ends, with some indication of the power requirements, temperature effects, and the like. Types of superchargers are discussed, and their systems of drives, and then particular attention is devoted to the General Electric turbosupercharger, as used on the Boeing Flying Fortress, Consolidated Liberator bomber, and Lockheed Lightning, and Republic Thunderbolt pursuit ships. Final sections of the paper are concerned with a comparison of various types of superchargers, and the present and future prospects for this most important aircraft-engine auxiliary.