This dissertation explores the rhetorical concept of ethos as it functions in contemporary online communities, via a case study of one successful online community, MetaFilter.com. A year-long virtual ethnography of MetaFilter demonstrates that understanding ethos as it functions online requires a multilayered definition that accounts for the traditional notion of ethos as vir bonus, the strict Aristotelian conception of ethos as textual element, and the pre-Aristotelian idea of ethos as "gathering place." It also documents the unique strategies employed by digital rhetors to establish and maintain their individual ethos, evaluate the ethos of their interlocutors, and shape the collective ethos of the communities to which they belong. Finally, it argues that ethnographic research in digital environments necessitates a mixed-methods approach for collecting, coding, and analyzing data. This study employs a limited number of quantitative measures and a variety of qualitative measures to analyze four types of data: (1) statistical information from the MetaFilter database (2) archived discussion threads from one of MetaFilter's forums, MetaTalk, (3) survey responses by MetaFilter members, and (4) interviews with the community's moderators. After presenting the study's findings, the dissertation concludes by indentifying four paradoxes manifested on MetaFilter that can help researchers, practitioners, and teachers of digital rhetoric better understand online communities and the essential role of ethos within those communities.