The role of principal as instructional leader is one that is not only vital to student outcomes but requires support from district level leaders to develop. This study investigated how practicing administrators understand the meaning of being an instructional leader focused on learning and how district leaders can support principals to develop their capacity. The purpose of the study was to examine principals' learning needs and to gain a broad understanding of the structures, supports, and resources districts and district level leaders should provide to effectively support principal growth and development. To understand this, this study used an embedded comparative case study approach designed to investigate beliefs, viewpoints, practices, and experiences of principals and district level leaders who are responsible for principal development, supervision, and evaluation. Interviews with multiple administrators in four medium-sized suburban districts provided the data to conduct within-role, across-role, and between-district analysis. Findings from the study revealed a limited common definition for instructional leadership focused on learning, with consistency only centering on one element: "understands the instructional practices being implemented" in classrooms. Respondents identified providing a system-wide "structure for principal and leadership learning" as a key district support. Finally, there was broad agreement among participants regarding how principal supervisors support principal growth and development. Both principals and their supervisors identified "mentoring and partnership practices" along with "creating a culture of adult learning," as most effective. Some "system processes" and "coaching approaches" were also identified as beneficial. These findings equip principal supervisors with a starting point for providing effective support to principals to guide and enhance growth and development. However, these findings also suggest districts may have additional work to do to establish a common understanding of leadership for learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]