This mixed-methods, content analysis study examined, identified, and described the characteristics and ways in which music educators participate and promote teaching and learning through discourse in an online community. Participants were members of an online social media community, the Facebook Music Teachers (FMT) group page. Using a theoretical framework of Wenger's (1998, 2006) community of practice, data collection included observing and analyzing the member posts/comments, specifically the frequency and types, as well as the language and discourses used. Members' interactions were quantified by developing an Index of Interaction (IOI), which is a sum score of (a) number of comments, (b) number of individual FMT group members who commented, and (c) number of "Likes." The posts yielding the highest IOI scores were qualitatively analyzed based on the types of comments they received. The commenting interactions were multidimensional and included moments of empathy, frequent activity, "following," and antagonizing. The dialogues, levels of participation, and group communication suggest that the FMT group is an online music community of practice. Social media may play a valuable role in providing a communal space for a shared purpose. These findings suggest that music teachers may benefit from new conceptions of professional development. Finally, we suggest that participating in an online community of practice, specific to music education, provides music teachers the opportunity to interact with colleagues to acquire new knowledge and reflect. [ABSTRACT FROM AUTHOR]