Online fan communities have revolutionized the way sport consumers engage with fellow fans and the sports product. The traditional regional boundaries that once characterized sports fandom have been mitigated by the emergence of new media, social media platforms, and online fan communities. This dissertation explores the non-geographically bound nature of contemporary sports fan communities, examining the evolving dynamics of fan behavior in the digital age. In Study 1, an interactional perspective is employed to explore online fan socialization. The focus is on how new fans' self-presentation influences acceptance within NFL team-specific Reddit communities. Utilizing data mining, textual analysis, and qualitative coding, the study reveals that the presentation of new fans significantly impacts community acceptance, shedding light on the foundations of online fan socialization. Study 2 investigates a newly formed online fan community for a professional sports team, aiming to understand how sport fan communities negotiate and establish brand community markers through discourse. Drawing from the communities of practice framework and discursive psychology, the study explores the development of a collective identity over time. Analyzing posts from the team's announcement through their second season, this investigation provides insights into the negotiation of community meaning and the construction of norms and prototypes. In Study 3, a holistic examination of online fan behavior explores how members engage with other communities beyond their primary team's community. Utilizing data mining and content analysis, the study investigates how online sports fans incorporate other online communities (e.g., other teams, sport-related communities) into their broader online fan experience. This exploration offers a nuanced understanding of diverse identities enacted within digital sports spaces, with a focus on sport fan maximizing behavior. Collectively, this dissertation contributes to the expanding body of research on online sports fandom, providing valuable insights into the intricacies of fan socialization, the negotiation of collective identities, and the multifaceted nature of online fan behavior. As the sports landscape continues to evolve in the digital era, this research seeks to deepen our understanding and enhance the scholarship surrounding the online sports fan experience.