Focus on the development of instructional leadership skills for school principals in the U.S. continues to be at the forefront of educational research and reform in response to the increased call for accountability. In this article we review relevant literature regarding instructional leadership from a historical perspective, then present a conceptual framework of instructional leadership in the 21st century. Using the Principal Instructional Management Rating Scale (PIMRS), we examined perceptions of principals, who had attended an Assistant Principals' Academy and who had recently matriculated to a head principal position, regarding their instructional leadership behaviors. We compared principal self-reports to perceptions held by teachers of instructional leadership behaviors in which their principals engaged. Data generated by the PIMRS were used to identify patterns of principal leadership. Our quantitative study of a cluster of principals (N = 9) revealed no significant differences between principal and teacher (N = 296) ratings of instructional leadership behaviors. However, further investigation revealed that the magnitude and direction of principal-teacher differences vary among schools in the sample study, suggesting that further investigation into the reasons for these differences is indicated.