School mass shootings have been increasing, leading to the need to better understand how exposure to these events affects high school and college students' academic performance, psychosocial functioning, and mental health. With a greater understanding of these effects, results can be used to inform the contemporary literature on the psychological and psychosocial consequences of mass shootings, which may, in turn, facilitate the future development of campus-wide preparedness plans for dealing with these events. The purpose of this quantitative systematic review was to illustrate the prevalence and patterns of the mental health, psychosocial, and functional consequences of school mass shootings in high school and university students and what factors influence mental health consequences through a narrative synthesis of the literature. A PRISMA flow diagram was used, and a total of 50 articles were included in the analysis. The results show school mass shootings are associated with various adverse psychological outcomes (e.g., posttraumatic stress disorder [PTSD], acute stress, depression, anxiety, fear, and substance use) both in the immediate aftermath and the long term. Less is known about the psychosocial and functional consequences; however, there is evidence that safety concerns, social interactions, and academic performance and adjustment are critical in victims' recovery. Though most individuals gradually recover over time, the data also show some individuals will continue to experience serious lasting adverse effects (e.g., PTSD, depression, and altered self-view and worldview). Furthermore, there is evidence for increasing the availability of mental health services around sensitive periods like anniversary dates. Although direct exposure is associated with more severe outcomes, findings also reveal indirect and media exposure can result in adverse consequences, which highlights the need for services across varying levels of exposed student populations. A variety of risk and protective factors have been identified, including demographic characteristics, pre-event trauma exposure, psychiatric history, level of event exposure, coping strategies, and psychosocial support. Limitations and factors leading to bias are discussed. Recommendations for future research and intervention are offered. [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.]