A research project was conducted to study the effects of an 8-week prekindergarten enrichment program and of two 15-month preschool enrichment programs. Pretest and posttest scores of experimental and control kindergarten children (a sample of 100 out of 1,000 subjects) showed that both groups made significant gains in all ability categories o f the Caldwell Preschool Inventory (CPI). The experimental group made significantly greater gains in numerical concept activation. In the preschool study (100 children), subjects in both experimental groups made greater gains in verbal ability (Peabody Picture Vocabulary Test) than the control group. On the CPI, children in one program gained in areas of personal social responsiveness and sensory concept activation, while children in the second program gained in both areas of concept activation, sensory and numerical. Preschool children in both programs made greater achievement gains than did control children. It is possible that greater motivation to learn was fostered by the enrichment program. About 2/3 of this report is made up of appendixes of tables and of forms used in the study. (MS)