This work explores the use of multimodal communication in a community of expert "World of Warcraft"® players and its impact on politeness, identity, and relationships. Players in the community regularly communicated using three linguistic modes quasi-simultaneously: text chat, voice chat, and face-to-face interaction. Using the ethnographic methods of observation, interviews, discourse analysis, and autoethnographic writing, modes are presented with a dual-function: as resources to use within interactions, as well as heuristics which shape the form of interactions. Within interactions, the modal affordances constrain the use of modes, leading to the phenomenon of "mode-switching" within individual interactions to take advantage of these differences. Not all players make the same choices, however; player identity is a factor influencing mode choice in broader interactional contexts. The assumed heterosexual masculinity of the "World of Warcraft" culture results in non-native English speakers, young players, non-heterosexual players, and women reporting avoidance of voice chat in situations with uncertain social expectations because they may face harassment about their identities. However, habitual avoidance of voice chat is also practiced by isolated individuals who engage in identity deception, resulting in voice chat avoidance being a marked practice that raises suspicions about player identity. Because multimodal communication is an essential component of interaction in the community, players who do not identify as heterosexual adult males find themselves in a double-bind of potential harassment or if they do use voice chat and suspicion if they do not, both of which may result in exclusion from communities and activities. This work demonstrates that multimodal discourse analysis, though often overlooked, is an essential component of research on virtual communities. Modes of communication are embedded in the linguistic fabric of a community, and choice of mode is a salient resource for navigating the social landscape. [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.]