Educational practitioners have attempted to use online technology such as Facebook (FB) in recent years to incorporate learning into students' daily social media usage. Past studies have explored FB affordances for informal learning, with a lack of investigations on interactive patterns among course participants, especially for learners in East Asian contexts. To fill the research gap, this study adopts the community of inquiry model (CoI) in an attempt to find out (1) how interactions on a FB Group facilitate the formation of an online learning community in Taiwan, and (2) students' and teacher's experiences of using FB Group for English learning. Content analysis of the group page through thematic coding, and Chi Square tests resulted in significant relations among interaction types, initiation type, and response type for the posts. Semi-structured interviews further yielded more positive than negative experiences associated with the FB usage. The results are discussed in relation to three elements of the CoI, with an indication of a strong teacher presence for fostering the online learning environment in this particular learning context.