Thin high-efficiency triple junction GaInP/GaAs/Ge solar cells have been incorporated into prototype flexible blanket coupons with a coupon efficiency of 28% for AMO (0.1353 W/cm2). Prototype coupons have a specific power density from 360 - 500 W/kg and may well approach >1000 W/kg with further thin cell and blanket fabrication improvements. Initial LIV results are shown for a thin flexible three-cell and twelve-cell coupon utilizing fully active triple-junction solar cells. This paper will outline the fabrication of prototype three and twelve cell flexible coupons, and initial illuminated I-V (LIV) test results under a large area pulsed solar simulator (LAPSS) at Spectrolab and discusses the advantages and applications of thin flexible GaInP/GaAs/Ge solar blankets. Thin flexible triple-junction solar cells have been demonstrated and incorporated into electrically active prototype blankets with specific power of 500 W/kg.