The purpose of this study was to explore teacher leaders' and principals' perceptions of instructional leadership in a shared context. The multi-stage multiple-case study examined roles and relationships of teacher leaders and principal teams across four schools within a Midwestern urban school district engaging in what has been identified in research as shared instructional leadership. This was a qualitative multi-stage multiple-case study, using interviews, focus groups, observations, field notes and archival information as data sources. An inductive approach was used to condense varied raw data into a summary format, to establish clear links between the research objectives and the findings derived from the data, and to develop a conceptual schema. Naturalistic inquiry assisted with the examination of this construct within the context of these individuals' human experiences. Six research questions served as a framework for the data collection. Research results conclude shared instructional leadership meaning is consistently identified with working with others and collaboration amongst all four teams of teacher leaders and principals. Roles of emerging teacher leaders and principals reconceptualized by educational reform parallel much of what has been discovered in previous research. District level job descriptions and performance expectations provide explicit indicators for role performance, revealing some of the ambiguity of their respective roles as principals and teacher leaders. Many similarities existed across all four schools. The relationships among teacher leaders and principals were quite favorable. A number of factors contributed to this result: support, mutual respect, trust, job performance, and district level expectations initiated by systemic reform. [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.]