Social determinants of health (SDH) are social and economic systems that directly contribute to health disparities and inequalities. This study examined SDH and their relation to education, also an SDH. The relationship between SDH and online undergraduate achievement, as measured by grade-point average (GPA), was studied. Cumulative inequality is the theoretical framework that guided the study; it underscores the complexity of interaction between personal, social, and environmental stressors in relation to a student's academic performance. The quantitative survey design allowed for potential relationships between variables to be observed and studied based on the survey responses per self-report from 212 online degree-seeking undergraduate participants. The dependent variable was GPA in an online undergraduate program of study. The predictor variables included household income, neighborhood safety, housing stability, and adverse childhood experiences. Mental health served as a potential mediator variable. Although there was a significant relationship between mental health status and GPA, mental health status did not mediate the relationship between the SDH and GPA. The conditions for mediation to occur were not met. There was no significant relationship between the SDH and GPA, nor a significant relationship between the SDH and mental health status. The data presented are valuable to post-secondary educators, academic advisors, stakeholders, and online students appropriate programming and advancement in academic resources. Increased achievement of undergraduates has a direct impact on positive social change. [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.]