This study aims to determine the relationship between school administrators' leadership styles and the collective teacher efficacy based on teachers' perceptions. In line with this objective, the multifactor leadership style scale and the collective teacher efficacy scale were applied on 223 teachers who were working in the province of Erzurum. Pearson's Moment Correlation Analysis and Multilinear Regression Analysis techniques were utilized in analyzing the obtained data. It was concluded that there was a significant relationship between school principals' leadership styles and the collective teacher efficacy. It was also found that the school principals' transformational, transactional and Laissez-faire leadership styles had the power to predict the collective teacher efficacy at a significant level.