The concerns for limited availability of petroleum based fuels and the upward cost spiral of oil has resulted in great interest in fuel consumption in the aviation sector of transportation. NASA has conducted studies to identify and accelerate the development of promising advanced technologies appropriate for achieving fuel conservative aircraft for the next generation of commercial transports. Several advanced technologies in the airframe and propulsion disciplines have been identified by NASA, with the turboprop being one of these. Two decades of turboprop technology advances are discussed along with their application to a Prop-Fan propulsion system for modern high-speed commercial aircraft. The Prop-Fan propulsion system features a small diameter, multibladed propulsor geared to an advanced gas turbine engine. The Prop-Fan's substantial improvement in thrust specific fuel consumption over the turbofan for operations up to Mach 0.8 as well as its acoustic character in the far and near field are reviewed. A more in-depth look at nacelle arrangements, component technologies, system weights, and reliability and maintenance is included.