The purpose of this study is to explore teacher community's practical knowledge. For this purpose, indischool, an online teacher community, was selected and how teachers' practical knowledge was developed in indischool online teacher community was investigated. Various methods were used to collect the data, including the observation of online activities in indischool website, interviews with indischool teachers, gathering the artifacts, and so on. The findings showed that indischool online teacher community collaboratively constructed the shared practical knowledge through externalizing the individual teachers' tacit practical knowledge, sharing it with the members of community, putting the shared practical knowledge into practice and testing, and reconstructing the shared practical knowledge. Through the cyclic process of externalizing, sharing, practicing, testing, and reconstructing, indischool online teacher community continuously developed the shared practical knowledge. Base on these findings, a community approach to teachers' practical knowledge was discussed