This study investigated the ecological factors that affect structural school reform implementation in Israel. The sample used was the whole student population that appeared in the 1972 census. By raising educational achievement levels, restructuring the learning sequence, and rezoning ethnically and economically segregated areas to promote integration, school reforms aimed at reducing the achievement gap between Jews from Asia and North Africa and those from Europe and North America. The study hypothesized that the larger the community and the higher the percentage of Sephardic Jews (whose origins are either European or North American), the greater the likelihood of realizing structural and educational school reform objectives. The research concluded that larger communities in Israel were more receptive to school reform initiatives; however, ethnic heterogeneity diminished the pace of reform implementation and consequent student performance. While the reforms improved Israeli student educational performance as a whole, larger more developed communities developed further, while the smaller communities, with their preponderant population of Jews from North Africa and Asia, did not progress enough to close existing performance gaps. (JAM)