This research investigates the learning impact of Montessori prekindergarten training as compared to traditional approaches with economically deprived Puerto Rican and Negro children. The three-part, 156-page monograph includes a 22-page introduction to Parts I and II, and a 37-page appendix to Part I. Parts I and II assess training effects of the first year of schooling, focusing on children beginning prekindergarten at approximately 4 to 4 1/2 years of age. The basic research design also includes an evaluation of training for children beginning school at 3 to 3 1/2 years. Part I contains an evaluation of perceptual and cognitive abilities. Part II investigates pupil preference for cognitive styles typifying ego strength in the young child and relevant for autonomous problem-solving strategies. Part III includes a follow-up assessment conducted at the end of kindergarten in order to investigate the cumulative effects of training over a longer period of schooling. The appendix to Part I contains age, sex, and ethnicity trends for the population investigated, a 25-page description of the test battery, a sample teaching log monthly checklist, and a list of sample questions for teacher interviews. The monograph also includes a list of 54 references used for Parts I, II, and III. (JF)