The purpose of this study was to examine whether instructional leadership functions, as defined in Hallinger's Principal Instructional Management Rating Scale, positively influence collective teacher efficacy to improve school achievement. Teachers from sample schools provided data for measures of collective teacher efficacy and instructional leadership, while school report cards provided data for measures of socioeconomic status and school achievement. The authors used these data to test their hypothesized model of school achievement via path analysis. They identified school socioeconomic status as a stronger predictor of student achievement than either instructional leadership or collective teacher efficacy. (Contains 8 tables and 4 figures.)