The Westinghouse Learning Corporation and Ohio University carried out a study on the impact of Head Start for the Office of Economic Opportunity. The main inquiry of the study concerned the difference between Head Start first, second, and third graders and non-Head Start first, second, and third graders in intellectual and social-personal development. Data were collected from tests, interviews, and questionnaires of students, parents, and teachers from 104 Head Start centers across the country, and control areas. The major conclusions drawn from these data were: (1) Summer programs are ineffective in producing lasting gains in affective and cognitive development, (2) full-year programs are ineffective in aiding affective development and only marginally effective in producing lasting cognitive gains, (3) all Head Start children are still considerably below national norms on tests of language development and scholastic achievement, while school readiness at grade one approaches the national norm, and (4) parents of Head Start children voiced strong approval of the program. Thus, while full-year Head Start is somewhat superior to summer Head Start, neither could be described as satisfactory. Further research aimed at the development of an effective preschool program is recommended. (MH)