The key results of a NASA-sponsored study of a large multipurpose launch concept are summarized. The study evolved, through parametric performance and detailed design analyses, the characteristics of an attractive launch vehicle approach for consideration in future mission planning studies. The reported vehicle system has only two stages: a LOX/LH2 main stage and a solid-motor strap-on stage. The main stage has the performance capability to fly single-stage-to-orbit and the structural capability to accommodate strap-on stages to achieve a broad range of payload flexibility. The salient features of the vehicle system, sized to deliver one to four million pounds to low earth orbit, are described. The major resource and technology implications of the system are discussed.