Recent scholarship at the intersection of Online Communities (OC), marginality, and novelty has emphasized that individuals with marginal social identities (outsiders) make novel contributions to an OC. It posits that outsiders, unmoored from the conventional wisdom of the insiders of a focal OC, can inject unique information, ideas, and perspectives, thus aiding in situated learning and allowing the community to chart new courses of action. While this literature has made valuable additions to our current understanding of the subject, it overlooks the following problematic: for a contribution to be considered novel it must be accepted as legitimate by the core of an OC (insiders). The legitimation of marginal novelty is an inherently puzzling process, because the same outsiderness that bestows marginal members’ with distinctive ideas also signals their lack of credibility and prevents them from shepherding the resources necessary to increase the legitimacy of their contributions. Furthermore, while outsiders may contribute the occasional novel ideas, it’s the legitimation of such contributions that increases the social embeddedness of outsiders and secures the regular inflow of new ideas. This raises the question of how the legitimation of marginality unfolds in an OC. I explore this question through the case study of a football discussion forum. By mapping the trajectory of three novel ideas which were introduced by two marginal identities (women and Gen-Z), I theorize that legitimation of novel ideas is dialectical process in which insiders and outsiders engage in identity practices. Furthermore, adopting a material agency perspective, I theorize that the underlying platform and its features are strongly implicated in this dialectic. This dissertation contributes to current literature by adopting a social constructivist understanding of novelty and showing that legitimizing/delegitimizing marginality is a complex labyrinth of insider-outsider interactions involving both social and material agency.