This qualitative, practitioner research study, conducted by a school leader-as-researcher, was designed to gain insight into instructional leadership and teacher learning through the perceptions of high school teachers participating in a voluntary, school-based, self-organized, self-directed, cross-curricular teacher learning group within a diocesan, Catholic secondary school setting. Using qualitative research methods to gather participant perceptions, the study explored the work of the group, its impact on participants in relation to self, students, colleagues, and the larger school family, and the role of the instructional leader in relationship with the group. Using lenses of instructional leadership, adult learning theory, the relationships between knowledge and practice, and professional/teacher learning communities, I analyzed the legitimacy of this particular type of teacher learning and highlighted leadership dilemmas that may be encountered when a voluntary teacher learning group self-directs. These conceptual frameworks also allowed opportunities to think about issues and practices that matter to an instructional leader and to challenge assumptions about teaching, learning, and leading within a strong, academic tradition in a resilient secondary setting. The inquiry provided a rich analysis of one context through which educational leaders may expand their understanding of teacher learning in different educational settings. [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.]