In this session, I will discuss about a professional development model that shows a powerful potential in allowing teachers to learn together as they inquire in classrooms and engage in reflective activities that would have implications for research. Lesson Study, which originated in Japan, is now being conducted in many other countries, including Southeast Asia. It is desired that by the end of this talk, participants would be able to consider this practice as a way to facilitate amongst them a stance of being researcher-practitioners, with implications for sharing their experiences and learnings inside mathematics classrooms via demo-teaching, research presentations, or publications.