Development of improved dummy lower extremities which are compatible with both the Hybrid III design and with other advanced torso designs is continuing. The first task was to establish the design and performance requirements for these new crash dummy components. To achieve this, an extensive literature review of relevant biomechanical studies was carried out and a detailed accident investigation of crashes involving lower extremity injury was performed. Finally, detailed discussions were conducted with biomechanical and clinical experts. The innfromation gained through these efforts was synthesized into a detailed set of design goals and requirements for the improved lower extremities, which are summarize in this paper.