There is a growing consensus that schools and practising teachers can, in collaboration and/or in partnership with higher education institutions, make valuable contributions to initial and continuous teacher development, specifically when teachers can see how their efforts result in improved student learning and achievement. Learning Study, a Hong Kong version of the Japanese Lesson Study, was developed and used as a tool in a three-year project (2000 - 2003) for improving teaching and learning. Learning Study, which is built on a school-university partnership model, and is grounded in a theoretical framework of variation (Marton & Booth, 1997), was found to be powerful for teachers' professional development. In four years' time, Learning Study has spread from two primary schools to over a hundred primary and secondary schools, and over a hundred Learning Studies had been developed. Learning Study was also used in mentoring to facilitate the forming of a "learning community", to supplement the one to one mentor-mentee model, where the professional growth of all teachers involved was enhanced. In this symposium, we will illustrate how learning communities can be facilitated through engaging teachers in action research cycles of Learning Studies, in which teachers are empowered to learn from their students, from each other and from research as well.