This work approaches the concept of social media engagement through a lens of participation theory. Following the work of Goffman (1981) and others, this dissertation uses the concepts of the participation framework and the participant role to explore engagement as a function of participation in interaction. The purposes of this dissertation are three-fold: to model participant roles as they are built in interaction on Twitter, to discover the ways in which participation is established through the linguistic choices enacted by participants, and to demonstrate the role of the medium as an important factor influencing possibilities for participation. Using discourse analysis as a methodology, tweets from accounts associated with National Hockey League (NHL) organizations are analyzed for the linguistic resources that are used to reference interactional roles traditionally understood as "speaker" and "hearer". In turn, the linguistic and discursive resources deployed in team tweets are used to reveal these speaker and hearer roles as more detailed and complex production and reception frameworks. The modal affordances of Twitter are also investigated as to their role in influencing the building of participation frameworks through talk, including unique linguistic forms that are available to Twitter users and possibilities for hiding or revealing participants through the Twitter screen. The findings of this investigation reveal three primary models for production frameworks for NHL accounts: an Impersonal Model that eschews identification of the parties in production roles, an Interpersonal Model that highlights the individuals involved in the interaction, and a Team Model that obscures the individual to focus on the team or organization as a primary participant. Additionally, a framework for understanding recipient audiences on Twitter is proposed, incorporating both actual and intended audiences. Consistent patterns in the language choices used to construct participatory identities for production and reception roles are demonstrated, highlighting the value of using linguistic data as a resource for investigations of participation. Finally, Twitter's modal affordances are shown to be an integral part of the ways that users enact participatory concepts, such as co-presence and address, revealing the importance of considering the role of the medium in participation studies. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]