Teachers are often at the lower end of hierarchical school leadership structure. However, school improvement literature suggests a non-hierarchical model, where teachers are key players in bringing about change, is more effective. Distributed leadership has been proposed and one approach to the distribution of leadership in schools is teacher leadership. Teacher leadership recognizes the important contribution of teachers to school improvement and brings to the fore the emergence of excellent teachers who have demonstrated leadership capabilities at the same time. This study explores perceptions and practices of teacher leadership in an established non-profit private school in Karachi, Pakistan. A qualitative research approach was adopted, specifically case study methodology. A private school was chosen as the research site and the participants included 4 teachers and the school’s principal. Data was collected via one on one semi structured interviews, teacher observations, field notes and review of school documents. The study found that all 4 teachers perform leadership roles in their individual capacity, they are all informal teacher leaders and do not require a formal leadership title or position. It is believed that all teachers possess certain leadership qualities and their potentials as leaders are geared towards improving student learning and raising students’ performance standards in collaboration with colleagues and the school’s leadership. The issues related to major policy shift are usually outside of teachers’ field of action. The data suggests that teachers flourish their leadership skills in their areas of interest and expertise. So teachers’ buying in job responsibilities is crucial as they do not bring innovation in the work imposed on them. The biggest hurdle in teacher leader practices is lack of time and opportunities available to them for collaboration and group decision making. Recommendations from this study include recognizing teacher leadership in the school’s reform agenda, encouraging teacher leaders to accept leadership work and giving attention to developmental programmes for teacher leaders.