This paper traces the development of research concerning effective schools and provides a critical, synthesizing overview of various research strands. Strands of research included are self-concept, teacher expectations, democratic-authoritarian leadership, various uses of the term "school climate," input-output production models (with particular emphasis on the 1966 Coleman Report), econometric studies, case studies, and status attainment literature. The paper stresses the converging lines of these various research perspectives and discusses methodological issues which were involved in the gradual change in the public's attitudes, from "schools do not make a difference" to "schools can make a difference." The issue of educability is raised with respect to possibilities for large-scale educational improvement based on the effective schools research. Two opposing values, economic efficiency and equity-effectiveness, are related to beliefs about the distribution of ability. It is suggested that educational policy and school improvement are determined more by political and economic choices than by research on state of the art school effectiveness. A 16-page bibliography is included. (JMK)