The purpose of this exploratory single case study was to focus on a high school principal’s enactment of high-leverage leadership practices that positively influenced teachers’ instructional practices in one high-performing high school in Alberta with a student population above 1,000. Four competencies were examined: (a) embodying visionary leadership, (b) leading a learning community, (c) providing instructional leadership, (d) and developing leadership capacity in determining a shared instructional leadership approach. The study included 10 participants: one principal, three vice principals, five teachers, and one long-serving superintendent within the school authority. The theoretical framework was based on a systems thinking approach. Analysis of the data collected from interviews, documents, artifacts, and reflective journals yielded 11 findings: (a) redesigning the organization; (b) cultivating strategic alignment to the vision; (c) facilitating shared responsibility; (d) promoting and participating in learning and development; (e) developing a robust mentorship program; (f) managing the instructional program; (g) fostering student-centered instructional approaches; (h) improving visibility and accessibility; (i) being data informed; (j) establishing a distributed leadership structure; and (k) identifying, empowering, and recognizing staff. This study concludes with recommendations, including the key recommendation of making a long-term investment in developing a shared approach to instructional leadership capacity at the jurisdiction and school level to support teaching and learning.