Principal leadership matters. While school principals impact student achievement in mostly indirect ways, the cumulative effect of their agency to design the school program, organize teacher and staff interactions and opportunities to collaborate, and make other important decisions that influence the culture of the school meaningfully affects the experience of staff and students. This research into principal leadership has sought to make a contribution to the understanding of what makes principals effective in their work. The existing research into what makes principals effective has consistently found that any single theory of leadership, like "instructional leadership," in isolated application will not be fully effective across all contexts. Rather, an integrated theory of leadership that recognizes the complexity of the principal role, the necessary emphasis on collective responsibility and action, and the significance of the school context is necessary in order to explore and extend the understanding of effective school leadership. Leading from an inquiry stance offers a framework for principal leadership that builds upon this existing research literature about effective school leadership. Therefore, this study sought to understand what leading from an inquiry stance looked like in practice and its impact on the culture of collaboration among teachers. The findings of this research study indicate that leading from an inquiry stance promotes the culture of collaboration among teachers, "anti-inquiry" practices undermine the culture of collaboration among teachers, and relational trust between principals and their teachers is a critical attribute for effective leadership around a shared vision of school improvement. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]