This paper reviews seven studies comparing the differential effects of early childhood programs and approaches on children's development: (1) Planned Variation in Head Start; (2) Planned Variation in Follow Through; (3) Soar and Soar Study of Follow Through; (4) Miller and Dyer's Planned Variations Study; (5) Karnes Curriculum Comparison Study; (6) Ypsilanti Curriculum Comparison Project; amd (7) A Comprehensive Assessment of the Imapct of Schooling. Studies compared academically oriented programs with cognitive discovery programs and/or discovery programs. Academically oriented programs included the Englemann-Becker Distar Program, the Bushell Applied Behavior Analysis model, the University of Pittsburg Individually Prescribed Instruction model, the Demonstration and Research Center for Early Education model, and the Karnes' Ameliorative model. Cognitive-discovery programs included Weikart's High Scope Model, the Tucson Early Education Model, the Nimnicht Responsive Model, the Gordon Parent Educator model, the Responsive Environment Corporation model, the Montessori and the Ypsilanti Piagetian-based, cognitively-oriented curriculums. Discovery programs were Bank Street, the Education Development Center model, and traditional nursery school classes. Also mentioned was the Community-Integrated Approach. Studies compared student achievement on standardized tests and on measures of social, moral, self-concept, problem solving and personality development. (SB)