The Home Instruction Program for Preschool Youngsters (HIPPY) is a free 2-year family oriented early childhood education and parent involvement program for parents with limited formal education to help them provide educational enrichment for their 4-year-old and 5-year-old children. As of 1996, HIPPY programs serve over 15,000 economically disadvantaged families in the United States. This report presents the findings on the effects of participation in the HIPPY program through children's early elementary school years. It expands an earlier study to include an examination of the impact of HIPPY on home educational environment as well as school performance. While the original model validation report only evaluated effects at the end of the program, this report presents findings on the children 1 year later. Study sites were chosen in cities in Arkansas and New York. Sample and comparison sample sizes varied from 63 to 38 families in Arkansas depending on the time sampled, and from 25 to 66 in New York. Positive results for the first cohort studied in both cities were impressive. HIPPY students outperformed their peers in school as measured through objective tests and teacher ratings. These findings were not replicated in the cohort from the second study, and attrition analyses did not reveal a compelling explanation for this failure to replicate the results. Appendixes include the program manual, information and followup forms, and attrition analyses for both sites. (Contains 8 tables and 45 references.) (SLD)