The problem addressed in this study was the increasing number of former National Collegiate Athletic Association (NCAA) student-athletes who did not receive a diagnosis or treatment but experienced concussion-like symptoms and socio-behavioral consequences. The purpose of this qualitative phenomenological study was to discover the experiences and socio-behavioral effects of former NCAA student-athletes who experienced concussion-like symptoms but did not receive a medical diagnosis or treatment due to their injury being missed or concealed. The theory of planned behavior outlines how the formation of attitudes, subjective norms, and perceived behavioral control can create an individual's or group's attitude or "norm." The concepts in this theory are relevant to this study as they indicate the connection between concussion culture, the underreporting of concussions, and the number of former NCAA student-athletes who are still experiencing concussion-like symptoms. In this study, the qualitative research method was the preferred method because it provided the best exploration into the student-athlete experience. The phenomenological study was optimal, as it focused on studying an individual's lived experiences within the world. A non-probability, purposive sampling method was used to collect data from 12 former NCAA student-athletes to represent a small sample of a university population. Thematic analysis was used as a form of qualitative analysis via ATLAS.ti. The following themes were identified during data analysis to answer the research questions: (1) participants noticed inefficacy with the concussion protocol when implemented, (2) participants did not have a clear knowledge of what the concussion protocol consisted of, (3) participants experienced unreported concussions, (4) participants experienced mental/emotional, or social changes after their suspected concussion, (5) participants think that people view them differently after their suspected concussion, (6) participants are still experiencing side effects of their suspected concussion, even now, (7) participants used potentially toxic habits to cope. The interview questions the 12 participants answered has been coded and categorized into themes that correlate with each research questions and contextualized into this study. [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.]