This report describes the research design of a study that identified and evaluated a collection of reforms designed to enhance learning by altering the amount of and/or the quality of time devoted to learning. The study focused on the quantity and quality of time that teachers and students spent in school and, to a lesser extent, students' out-of-school activities. Researchers conducted case studies of 14 sites that had experimented with different ways of allocating time as a cornerstone of efforts to improve the quality of teaching and learning. All the schools served a substantial number of disadvantaged students. The sample included the following: (1) eight public schools and six private schools; (2) three elementary schools, five middle schools, two high schools serving grades 9-12, two secondary schools serving grades 7-12, one school serving grades 1-12, and one school serving students aged 16-21; (3) four residential schools; (4) eleven urban schools; (5) two schools that enrolled only boys; and (6) schools with student enrollments ranging from 20 to approximately 800. During the site visits, data were derived from the site-context record; interviews with teachers, administrators, and support staff; student focus groups; document analysis; and students' out-of-school-time diaries. Five exhibits are included. Appendices contain data-collection instruments and a list of reports derived from the study. (LMI)