This research focuses on the implementation of collegial supervision of teachers and their impact on teaching performance. Specifically, this study is for: 1) knowing the description of the implementation of collegial supervision, 2) exploring a number of factors that support and inhibition in the collegial supervision of teachers, as well as 3) the impact of collegial supervision on teacher teaching performance. The results of this study are expected to provide a comprehensive overview in implementing effective collegial supervision activities, and be informed for the principal in improving teacher teaching performance through collegial supervision programs implemented in schools.