The Learning Study approach has been developed over ten years by a research team comprising school teachers and academics in Hong Kong. It is a systematic process of enquiry into teaching and learning, employing an action research methodology, and underpinned by the Variation Theory. Under Learning Study, teachers are expected to learn cooperatively and become reflective practitioners by practicing the theories postulated from others. Learning Study can be used to enhance teachers’ pedagogical capabilities and professional development. This paper describes how Learning Study, which initially started as a modest project to find ways to cater for individual differences in main stream schools in Hong Kong, became a powerful tool for schools in achieving these aims. Working in close collaboration with the Hong Kong Institute of Education, Learning Study developed as a major component of a mentoring system, which resulted in the creation of learning communities in schools, where the focus is on enhancing teaching and learning. Such a system benefits all teachers involved, whether novice or very experienced. Starting with only two schools in 1999, schools in the Learning Study network rapidly expanded to over 200 schools in 2010. The success of Learning Study in Hong Kong will be analyzed under the following factors: its conceptual framework, methodology, partnership with higher education institutions, positioning, reform context and culture, and dissemination strategy and the diffusion process in and across schools. Its potential for moving towards improving the status of the profession as a whole will also be discussed.