To provide educators with a compilation of available data on the implementation and operation of year-round programs, this publication incorporates reviews of evaluative studies conducted by six year-round programs: the Prince William County, Virginia, 45-15 Plan; the Valley View, Illinois, School District, 45-15 Plan; the Dade County, Florida, Quinmester Plan; the Atlanta, Georgia, Public Schools Four-Quarter Plan; the Becky-David School, Missouri, 45-15 Plan; and the Chula Vista, California, 45-15 Plan. Studies were selected that are relatively thorough in both scope and evaluative procedures and representative in terms of the type of program evaluated and geographic location of the program. Program evaluations are reviewed separately because of the variability in type of program, school characteristics, implementation procedures, measurement tools, and other factors. Most of the evaluations analyze costs; student achievement; and the attitudes of the community, parents, students, and teachers toward the program. Several of the evaluations also discuss administrator attitudes and duties, and one program evaluation considers the effect of their school's year-round program on extracurricular activities. A 40-item bibliography is included. (Author/DN)