Michigan lawmakers funded a competitive grant program for school districts to plan and implement extended school year (ESY) programs of 200 days. The primary purpose was to raise academic achievement. In the spring of 1992, 16 diverse school districts were awarded ESY planning grants. Continuation grants funded 2 ESY implementation years, for plans of 195 or 190 student instruction days with 5 or 10 staff development days. Fifteen of the original districts continued implementation into the second year, and these programs were evaluated using program documentation, local district evaluations, administrative interviews, and surveys of about 2,500 ESY participants (students, parents, teachers, administrators, and other school personnel). Approximately 13,000 students participated in ESY programs, whether summer programs, extensions of the traditional school year, or year round education programs. After 2 years of implementation, ESY participants vary greatly in their perceptions of the program. In the most effective programs, all stakeholders report learning to be greater, and retention of skills over the summer to be improved. When ESY has not been successful, neither of these outcomes has been observed. The most positive results were found in the year round education programs, while programs extending the traditional calendar year were least successful. ESY programs were most successful when integrated into a broader plan for school improvement. Mandatory participation yields less favorable results than choice of the program. Appendixes presents district demographics and program features, survey instruments, and technical notes. (Contains 10 tables, 14 tables in an appendix, 28 figures, and 32 references.) (SLD)