Several elementary schools that drew their students from low socioeconomic (SES) areas and which succeeded in teaching reading were studied to determine the main causes of their academic achievements. Interviews, analyses of test scores and work logs, classroom observation, and reviews of school memos indicated two primary causes of success: achievement orientation and building-wide instructional efficiency. An achievement orientation, which generally must come from the building principal, is a high-risk, yet essential mode of operation in low SES areas, because it creates the conditions under which efficient instruction might develop. Instructional efficiency depends on adaptability and consistency of instruction, which, in turn, depend on the range of abilities in each classroom, the monitoring of student progress, the availability and coordination of personnel, the stability of the instructional program, and the program's compatibility across grade levels. School districts that want to raise reading scores should encourage principals to become achievement-oriented curricular leaders, both through inservice training and through principal evaluation procedures that focus on curricular leadership performance. (Author/RL)