We discuss the indications, technical pearls, and pitfalls of hip spica cast application in pediatric patients. The intent is to teach the proper technique for hip spica cast application and to avoid the known complications of this technique. Hip spica casts covered in this chapter will include spica casting for developmental dysplasia of the hip and for traumatic purposes including femur fracture application as well as a brief discussion regarding the commercially available braces for the treatment of various pediatric traumatic injuries. The figures and videos included will provide illustrations and examples of cast application, tips and tricks for applying these casts, as well as things to avoid. Key Concepts: (1) Respect the cast. Ensure that all areas are well padded with layers laid down without wrinkles or kinks. (2) Add additional splints of cast material to areas over joints where motion may occur to strengthen the cast without adding additional circumferential layers. (3) Patient and family education is critical to draw attention to problems early and to mitigate any unnecessary burden. (4) Understand what you are trying to accomplish with a spica cast to determine appropriate configuration (double leg vs single leg) and patient position (open hip reduction vs femur fracture management). (5) Ensure that you have collected all necessary equipment and resources before starting to allow for a successful spica cast application.