The glycidyl azide polymer (GAP) is an energetic, thermally stable, insensitive, hydroxyl-terminated prepolymer with Potential applications in advanced solid propellants including 1) class 1.3 nondetonable minimum smoke propellants, 2) clean propellants for solid rocket boosters, 3) gas generators/aircraft starter cartridges, 4) low-cost ASAT maneuver propulsion systems, and 5) high-performance space propellants for orbital transfer vehicles. The historical development of GAP from its conception is reviewed in this paper.