The reliability and validity of teacher ratings, the relationship between teacher ratings and principal self-reports of instructional leadership, and the degree to which they are influenced by demographic factors are examined in this study. Methodology involved completion of the Instructional Leadership Inventory, a self-report measure, by 81 principals and completion of the Instructional Climate Inventory by 1,700 teachers representing a cross section of suburban schools within the Chicago metropolitan area. Demographic variables were also analyzed. Results show substantial agreement between principal and teacher ratings of instructional leadership; however, factor analysis suggests that teacher ratings are influenced by their perceptions of school culture. Conclusions are that teacher ratings of instructional leadership have questionable validity in identifying specific principal behaviors that contribute to school effectiveness and that principal behaviors indirectly affect student outcomes. Nineteen tables are included. (LMI)