This chapter provides a detailed study of /r/musictheory, a large forum (“subreddit”) for music theory discussion hosted on the platform Reddit.com. Writing as two of the subreddit’s moderators, the authors outline the culture and structure of this public forum and examine the mixed realities of conducting music-theoretical discourse in such a space. The authors show how Reddit’s bottom-up, user-powered culture and pseudonymous user-name system simultaneously create unique environments for collaborative learning while also enabling toxic groupthink behaviors that subvert those opportunities by perpetuating epistemic injustices. The authors conclude the chapter by reflecting on the future of the subreddit in light of these findings.