Marijuana use has been linked to poor undergraduate student academic performance, yet cannabis continues to be the substance most often used by college students. The purpose of the current research was to add to the limited body of literature about the relationship between female undergraduate marijuana use and lower GPAs. The study explored how marijuana use impacted the GPAs of undergraduate African American females. The research question addressed whether a significant relationship exists between marijuana use and lower GPAs for this population. Complex adaptive systems theory was the lens used to better understand the phenomenon during a time of rapid social and public policy change. Secondary data were gathered from the American College Health Association/National College Health Assessment and tested using statistical regression analysis. Findings demonstrated a relationship between marijuana use and lower GPAs. Data analysis indicated that a significant negative association existed between marijuana use and lower GPAs of undergraduate African American females and females of other races. While a relationship was demonstrated, the correlation does not show causation: the nature of the sample and other drivers outside the scope of the study, such as admissions policies and socio-economic factors. Positive social change implications could include greater awareness on the part of policymakers, admissions and university officials, and other relevant stakeholders of the gaps in GPAs across populations. While social trends suggest that liberalization of marijuana laws may be loosening, stakeholders are recommended to consider responses such as intervention or education programs to close the gaps. [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.]