Cochlear implants seem to be the first long step in the search for a mechanical prosthesis that would restore hearing to the profoundly deaf. While present developments with implants appear to have been successful in providing deafened individuals with a reasonably wide range of information, the ultimate goal, the full comprehension of discriminable speech, is still beyond our grasp. The present monograph is essentially a history of how we arrived at this point in the development of cochlear implants. It begins with the original observations of Djourno and Eyriès, the first animal and human studies, and the early work of House and Urban with a small sample of subjects. The problems, failures, and initial successes are detailed, as well as an account of the engineering developments in which the hard wire electrode system with the external button was finally replaced by the more sophisticated internal induction coil with the “take-home” stimulator. Early in the project, it became clear that many specialists needed to be involved both for the purposes of evaluation and training of implant subjects. The first such individuals were rehabilitation experts and their program for defining objectives, procedures and evaluation is discussed. Since implants were likely to have potentially profound cognitive, emotional and social effects, a team of psychologists became participants. Their preliminary program and initial study is outlined. Finally, this history concludes with some observations about where we have been, the current stage of development, and plans for the future. It is our optimistic view that we are on the threshold of an important advance in the treatment of the profoundly deafened.