Collaboration between teachers is a significant predictor of outcome variables at the schools, teacher, and student levels. As they are in charge of establishing the work settings for teachers, principals have the power to encourage and develop teacher collaboration. The aim of this case study was to gain insight into how important principals’ roles are in establishing and maintaining a cooperative work environment between teachers. With the document analysis method, the paper is going to discuss principals’ roles in encouraging collaboration between teachers, the benefits of teacher collaboration, and links between principals’ roles and teacher collaboration. Hopefully, it would be a precious source for both principals and teachers to be aware of the importance of collaboration at tertiary level.