This article examines and critiques the leadership capacity of department leaders in a high school and attempts to gain a deeper understanding of how department leaders perceive their role as teacher leaders, making a distinction between what an individual department leader does in his or her position and teacher leadership as a form of continuous learning and innovation through collaboration. How do department leaders practice leadership to improve student learning? The author provides an investigation and analysis of the current level of leadership capacity exhibited by department leaders in a high school. A close look at the role and function of department leaders in this high school reveals an absence of the teacher leadership necessary to promote the broad-based leadership capacity that results in improved student achievement.