This chapter presents the theoretical and practical implications of research conducted on online learning communities at Purdue University using the Community of Inquiry lens. Specifically, highlights of eight studies conducted from 2013 to 2015 are presented. The context of the majority of the studies is the online Learning, Design and Technology Master's (MS) program. The research studies have provided theoretical and practical insights as well as directions for future research. Overall, this research points to the importance of empirically testing theoretical assumptions, which can provide unique insights into how to enhance both theory and practice in online education. [For the complete volume, "Educational Media and Technology Yearbook, Volume 40," see ED593960.]