To meet the growing need for high-quality research on whole-school approaches to instructional improvement, researchers at the University of Michigan School of Education, in cooperation with the Consortium for Policy Research in Education (CPRE), conducted a large-scale, mixed method, longitudinal Study of Instructional Improvement to investigate the design, implementation, and effects on student achievement of three of the most widely-adopted whole-school school reform programs in the United States: the Accelerated Schools (ASP), America's Choice (AC), and Success for All (SFA). Each of these school reform programs sought to make "comprehensive" changes in the instructional capacity of schools, and each was being implemented in schools in diverse social environments. Each program, however, also pursued a different design for instructional improvement, and each developed particular strategies for assisting schools in the change process. In order to better understand the process of whole-school reform, Study of Instructional Improvement (SII) developed a program of research to examine how these interventions operated and to investigate their impact on schools' instructional practice and student achievement in reading and mathematics. The research program had 3 components: a longitudinal survey of 115 schools (roughly 30 schools in each of the 3 interventions under study, plus 26 matched control schools), case studies of the 3 interventions under study, and detailed case studies of 9 schools implementing the interventions under study (plus 3 matched control schools). Across all components of the SII study, the research examined alternative designs for instructional improvement, alternative strategies for putting these designs into practice in local schools, and the extent to which alternative designs and support strategies promote substantial changes in instructional capacity and student achievement in reading and mathematics. The most comprehensive component of SII was a large-scale, longitudinal, multisurvey study of schools. The use of survey research methods was intended to track the course of schools' engagement in comprehensive approaches to instructional improvement and to investigate the conditions under which this led to substantive changes in instructional practices and student achievement in reading and mathematics. The study design called for each school to participate in the study for a period of three years, although some schools voluntarily provided a fourth year of teacher, leader, and school-level information (no additional student-level data). In addition, survey researchers conducted interviews, primarily a telephone protocol with a parent or guardian of each cohort student in order to gather information on students' family background and on students' home and community environments. Researchers also gathered data from school leaders and others about the policy environments in which the schools are located. Another component of the research program involved the development of detailed case studies of a small number schools participating in the study. The case studies gathered observational, interview, and documentary evidence to better understand how instructional change processes unfolded in different school settings. Case studies were conducted in 12 schools operating in differently configured state and district policy environments. In each environment, researchers selected schools participating in one of the interventions under study as well as a "matched" control school. Finally, case study data was used to chart key similarities and differences in the design and operations of the interventions under study, to analyze how different design features affect operating strategies, and to better understand the general problem of how intervention programs can work to devise and "bring to scale" a feasible scheme for improving instruction in local schools.