The primary aim of this study was to evaluate school principals' instructional leadership behaviours based on teachers' views. The instructional leadership model developed by Hallinger and Murphy (1985) was used, and the phenomenological design of qualitative research was employed. The participants were 16 teachers working at public schools in Turkey. The data were analysed using content analysis technique. The results showed that school principals performed well in some of the areas determined by Hallinger and Murphy while performing weakly in other areas. They performed strong behaviours in conveying the objectives of the school, organising the curriculum, being available, preserving the time allocated to instruction, appreciating teachers' success and monitoring student development. However, they were reported to show a weak performance in determining the school objectives, improving the curriculum, contributing to teachers' professional development and following student learning. Based on the results, it can be suggested that policy-makers should create favourable conditions for school principals to act more independently in curriculum development. Moreover, school principals should make an effort to ensure teachers' professional development and form a school culture that would strengthen professional cooperation among teachers. Above all, school principals' knowledge and expertise regarding instructional leadership can be enhanced by means of in-service training programs.