Abstract : With diminishing world fuel supplies, and a global increase in fuel price over the last ten years, the reduction of aircraft drag has become a technology of major importance to aircraft manufacturers. Likewise, advances in test and evaluation techniques have facilitated the accurate evaluation of drag and led to concurrent developments in drag prediction methods. A noteworthy development is the use of a number of novel flow control methods which, through either passive or active interaction with the flow physics, can lead to substantial drag reductions. This special course covers some of the more recent progress in drag reduction, measurement and prediction. The topics presented discuss the different sources and contributions to aircraft drag with particular emphasis on those areas in which significant new developments have taken place. The course begins with a general review of drag reduction technology. Then the possibility of reduction of skin friction through control of laminar flow is discussed, with design aspects of laminar flow control hardware included. The other possibility of skin friction reduction through modification of the structure of the turbulence in the boundary layer is also discussed. Methods for predicting and reducing the drag of external stores, of nacelles, of fuselage protuberances, and of fuselage afterbodies are then presented. Transonic drag rise, the prediction of viscous and wave drag by a method matching inviscid flow calculations and boundary layer integral calculations, and the reduction of transonic drag through boundary layer control are also discussed.