207 their natural limb. In Phase 1, the leveraging of COTS products coupled with prototypical technology development was demonstrated in the 7-degree-of-freedom (DOF) Prototype 1 system, which was fully patient tested in a clinical environment using noninvasive neural integration strategies. Prototype 2 improved upon this technological foundation to solidify subsystem design approaches and prove the viability of a highly dexterous (22+ DOF) system. At the system level, Phase 1 required the identification of advanced scientific research and engineering concepts to identify viable integration pathways to meet Phase 2 objectives. The ultimate deliverable for Phase 1 was a Systems Integration Plan to address the following topics: engineering development road maps, additional INTRODUCTION In 2005, the Defense Advanced Research Projects Agency (DARPA) started the Revolutionizing Prosthetics program in an effort to restore natural limb function to war fighters who had suffered limb amputations in the line of duty. Because prosthetic technology at the time was still rooted in concepts generated decades ago, the potential advancement in restorative function that advanced prosthetic devices could provide would be revolutionary. After two phases of development, DARPA envisioned by the end of 2009 a fully functional and neurally integrated prosthetic device that could mimic the natural function of the human limb to the extent that current technology would allow. DARPA charged that the device should look, feel, weigh, perform, and seamlessly integrate with the human user as if it were he development of the Modular Prosthetic Limb (MPL) has and continues to be the result of cutting-edge technology innovation in mechanical, electrical, and software design. Sound systems engineering practices have laid the foundation for the successes achieved during the Revolutionizing Prosthetics program. From the initial effort to prove, with Prototype 1, that an advanced prosthetic device is possible to the technology candidate elimination process undertaken for Prototype 2, the design methodology included extensive analysis of user requirements, system trade studies, and testing to engineer the MPL to meet challenging sponsor needs. To show how this remarkable technology came to be, we describe in detail the MPL development process. An Overview of the Developmental Process for the Modular Prosthetic Limb