The purpose of this multiple case study was to examine the role of social presence in a professional online conference. This study explored how presenters and attendees convey social presence and how might it influence their conference experience. The participants were presenters and attendees registered for the 21st Annual Teaching Colleges and Community Worldwide Online Conference (TCC Conference), a completely online event that occurred in Spring 2016. Without presenters and attendees being physically at the venue, how do presenters and attendees construct and convey social presence to build a learning community? The current surge of research to understand online pedagogy and learning has targeted the virtual classroom while few studies have been conducted on social presence in online conferences. This multiple case study involved both qualitative and quantitative data using linguistic inquiry and word count, transcript content analysis, constant comparison analysis, a survey and interviews, grounded in the Community of Inquiry (CoI) theory for studying online learning experiences. Ultimately, the study revealed that social presence was manifested in the volume and patterns of interaction in a professional online conference and can be studied using the CoI framework's social presence category. This was evident in the data gathered using multiple methods to observe and analyze what occurred during the 2016 TCC Conference and perceived experiences after the conference. Attendees projected themselves socially and affectively as well as formed perceptions of other attendees and presenters as "real people." For attendees, this was demonstrated by the way messages were posted in the chat box and how others interpreted those messages as well as how attendees interacted with each other and with the presenter using chat discussions. For the presenters, this was demonstrated by how they presented their content, how they interacted with attendees, what they did and what they said to engage attendees in the sessions within the context and tools limited to the computer mediated environment. The results of this study suggest that social presence can be established in a shorter time frame than previously thought possible compared to online courses conducted over a semester or term. Presenters and attendees participating in online presentations lasting 20 to 45 minutes were able to project observable instances of social presence. Other variables, such as presenter presence, content and delivery, attendee-presenter interaction, social media and previous relationships may have played varying roles in how social presence was established and maintained in a fully online professional conference. [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.]