This analysis of current research on prekindergarten programs for the disadvantaged covers more than 40 evaluative studies drawn from public school systems, program developers and federal agencies throughout the U.S. Findings from most of the studies included were made public between 1970 and 1975, although some earlier research is included. A tabular summary of each study is presented, describing program type, evaluation instruments used and results. This is followed by fuller descriptions of the individual studies which comprise the main section of the volume. School and home-based programs, migrant education and mobile classrooms are covered, as well as programs for the learning disabled and mentally retarded. A brief introduction discusses problems in the evaluation of research on prekindergarten education. An extensive bibliography, of both published and unpublished literature, is furnished for in-depth study of specific aspects of preschool education. (BF)