Methodological and practical challenges present formidable barriers to conducting empirical evaluations of school reform initiatives. Systematic information about school reform and improvement, and its relationship to special education, is even more difficult to obtain. In this study, the authors developed a reliable and valid method to (a) systematically describe and assess the school improvement process and (b) examine its relationship to special education by including in the investigation programs for students with emotional disturbance. A rigorous case-study design was used with 20 schools that varied in their levels of improvement activity. Results indicated that the School Improvement Index (SII) could reliably and validly discriminate between schools engaging in high levels of school improvement activities and those schools engaging in low levels. The use of the SII as a research tool and an aid to local schools engaged in school improvement is discussed.