With the growing number of online course opportunities in higher education, it is necessary to gain an understanding of the benefits of fostering social presence in those courses for adult learners. Ensuring that adult learners are provided with an online learning community that fosters social presence and promotes students' autonomy, competence, and relatedness to others is fundamental to their academic success. The purpose of this study was to determine how discussion strategies used in online courses work to foster social presence for adult learners and to identify the effects of discussion strategies on autonomy, competence, and relatedness in online courses for adult learners to achieve positive learning outcomes in higher education. A mixed-methods approach was used to identify the effects of text-based and video-based discussions on the perceived social presence, autonomy, competence, and relatedness of adult learners enrolled in undergraduate courses in the Interdisciplinary Studies program at a four-year college located in the Southeastern portion of the United States. There were ninety-eight students and three instructor participants. Each instructor taught two sections of the same course over a 16-week period. Each specific section consisted of an 8-week course. Student participants in the first 8-week course participated in text-based discussions, and student participants in the second 8-week course participated in video-based discussions. After analysis of the data collected, there were no statistically significant differences in social presence between the text-based and video-based discussions. Qualitative data revealed the importance of social presence in online courses for adult learners. Adult learners emphasized the value of being able to experience a sense of community and belonging in their online courses. Both groups described the importance of meaningful student-to-instructor interactions. Students were more comfortable using text-based discussions although reported experiences of a limited learning community specifically during their discussions. Both groups described having the ability to freely express themselves through their discussions. The study indicated there is a relationship between social presence and meeting adult learners' basic needs using text-based and video-based discussions in online courses. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]