摘要：As learning organizations, it is essential for schools and teachers to develop as a whole. For this purpos e, they must draw conclusions continuously from what they have experienced and adopt them to the changing environmental conditions. In this regard, in order to develop both individual and organizational capacity, teachers should observe their colleagues' instructional practices and give them feedback about their practices . It is possible with highly qualified teacher leaders. Teacher leadership is to have proficiency in taking on tasks voluntarily at classrooms and schools, develop projects , influence people around them, and support their colleagues' professional developments. In this frame, teacher leaders are the ones who are teachers, expert teachers, mentor teachers and supervisors. Therefore, the main purpose of this study is to determine teachers' teacher leadership perceptions. The study also aims to find out the definition of teacher leadership, teacher leaders' roles, appropriateness of their roles to the teaching job itself and their colleagues perceptions about teacher leadership. This study was carried out with a qualitative research design. The participants were 25 teachers who are currently working in 2014-2015 academic year in Istanbul, Turkey. Results reveal that teachers know what teacher leadership is and their roles are in the system. However, it is claimed that as their roles are not defined formally teacher leaders do not hav e freedom to implement what they hope to do. It was also concluded that teacher leadership roles are appropriate to the job they are currently performing and these roles are perceived positively by their colleagues. Teacher leaders are also claimed to have excessive workload and it is considered that this situation prev ents them from performing their leadership roles at schools. While some of the participants allege that their roles should be defined in the current system, some others argue that it must be kept the same in the system now because defining their roles in the system may cause some problems.
