This series of followup studies concerned mentally retarded rehabilitation clients of the Social and Rehabilitation Service research and development projects in the District of Columbia, and the Model Cities Project in Maryland. The clientele were primarily black, urban ghetto residents. The studies dealt with (1) vocational success of institutionalized retardates released for community placement; (2) vocational success of non-institutionalized retardates, successfully rehabilitated and closed for other reasons; and (3) vocational success of successfully rehabilitated retardates and non-retardates. Results indicated that a placement program which included placement homes, training, and job placement was imperative for vocational success of institutional adult retardates discharged to independent community status. These institutional dischargees also required long term post-employment services. For non-institutionalized mildly retarded clients, job training and placement according to potential were essential rehabilitation services which had sustaining effects on vocational success. For retardates the placement quality, reading ability, and absence of secondary disabilities were primary determinants of income at followup. Non-retardeds' income at "closed rehabilitation" was not indicative of their vocational success; income at the referral stage was an index of their future success. They primarily benefitted from the rehabilitation agency's restoration services; their socioeconomic status also had a bearing on their vocational success. (Author/CSS)