The purpose of this paper is to list the possible competitive engine systems for the STOL aircraft likely to be operational in the late 1970s or early 1980s. The importance of integrating the engine and airframe during the early design phase of the STOL aircraft system will be outlined. A description of typical augmented wing and blown flap engine concepts under investigation, and the system trade factors affecting aircraft gross weight and potential return on investment will be presented. System trade factors including noise, weight, performance, and cost will be evaluated to provide an overall view of the compromises that are, or must be made in order that the STOL aircraft engine system be a viable commerical product. The available and required engine technologies are reviewed.