As online education gains popularity among both learners and postsecondary institutions, there is a movement toward identifying ways to promote student success. Over half of all higher education institutions offer online classes, due in part to the ease of offering and scheduling (Hoffman, 2006); educators seek ways to identify any demographic or academic characteristics that lead to success (Jaggars & Bailey, 2010). With the growth and popularity of online learning, postsecondary institutions must continue to develop best practices in the areas of online teaching pedagogies to promote student success. Within community colleges there is a growing acceptance of online courses and given that over 60% of incoming students test into developmental math coursework (Chen, 2016), answers must be sought to assist these developmental math learners toward online success. This study investigated the role of various student characteristics concerning student success in online developmental math course completion. The sample was students enrolled in a specific identified gateway mathematic course offered fully online in at a large suburban, public community college located in the northeastern part of the United States. Utilizing a mixed methods explanatory sequential design, explored course completion rates of developmental students enrolled in online college-level mathematics courses, the study analyzed the role of demographic and academic characteristics for developmental students enrolled in a college-level mathematics course offered fully online from the fall 2017 through fall 2019 academic year. A second phase of semi-structured interviews was conducted to explore aspects of student success from individuals identified in the first phase. As the success of developmental college students is at the forefront of postsecondary institutions in their mission for student success online, the ability to identify characteristics that could lead to student success may assist in recommendations for online instructors and assessment of developmental math student college-level mathematics course completion. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]