The present state-of-the-art, technology, and theory applicable to deployable aerodynamic decelerators, especially textile parachute canopies, are presented. Major types of decelerators are described, and their aerodynamic and operational characteristics, as well as applications, are discussed. Detailed coverage is given to decelerator materials, design and construction, hardware, test methods and vehicles, and test instrumentation. Decelerator design procedures and performance prediction techniques are demonstrated by sample calculations.