Given the current focus on school evaluation and accountability, it is vitally important to capture those differences among schools that can be expected to contribute to student success as measured by students' behavioral, emotional, and academic outcomes. The current practice of comparing "district" and "charter" schools, for example, or "public" and "private" schools, obscures the more important differences that such schools may have and does not provide a basis for substantive conclusions. To truly understand school differences, we must go beyond the surface of simple governance issues to consider how, at a deeper level, schools differ from one another. This paper presents the results from an extensive review of schools (district, chartered, and private) and the school effectiveness research. Potentially important differences among schools are highlighted and the implications of these findings are discussed.