The Pegasus Air-Launched Space Booster development program, begun in early 1987, has the objective of combining an innovative approach to satellite launch operations with the latest in proven launch vehicle technology. Air launch of small satellite payloads on Pegasus provides a substantial performance improvement over ground-launched systems and also offers new launch operations flexibility including the ability to launch directly into virtually any orbital inclination. This paper describes the overall Pegasus vehicle design and reviews those design aspects that influence the design and integration of satellite payloads