The Space Station program was faced with a unique design environment-to design a common systems and payload support structure that could accommodate changeout for repair or technology growth over a 30-year lifetime. The vibration environment and weight allocation for rack structure necessitated a lightweight, yet stiff structure. The design answer was a modular rack structure using graphite/epoxy composites and selected aluminum components that could support a wide variety of systems, payload and stowage functions.A modular set of mounting locations allow the installation of a wide variety of secondary structures without permanent modifications to the rack. Aircraft-style seat track rails on the front edges of the rack permit attachment of handrails, foot restraints and accessories such as lights, fans, clipboards or computers to the rack face. The utility interface panel accommodates reconfiguration of the lines into a rack when rack-mounted hardware is updated, replaced or repaired.This paper describes the rack available to users, the packaging interfaces, and the modular features of the rack. It also traces the development history of the rack structure and provides some lessons learned on the design and integration processes.