Injury to the brain can range in cause, severity, and outcomes. Individuals with brain injury may experience both physical and cognitive... Show moreInjury to the brain can range in cause, severity, and outcomes. Individuals with brain injury may experience both physical and cognitive impairments. Not only can a patient experience a wide range of symptoms, these symptoms also can vary drastically in severity. Research has shown that these symptoms play a role in a person’s quality of life following injury: the worse a person’s symptoms are, the lower they report their quality of life. However, recent research suggests that psychosocial factors may mediate the relationships between disability severity and quality of life across multiple rehabilitation populations. Two of the previously researched psychosocial constructs include social support and a sense of mastery over the disability or disease. The purpose of this study was to examine a structural model hypothesizing the mediating role of these two constructs on the relationship between symptom severity and quality of life among adults with brain injury. Participants in this study included 183 individuals with brain injury recruited through state brain injury organizations across the United States to participate in an online survey study. Using structural equation modeling (SEM), results demonstrated good model fit. (χ2(15, n = 183) = 13.68). Normed Bentler-Bonnet fit index (NFI) was .97; Goodness-of-Fit statistic (GFI) was .98; Adjusted-goodness-of-fit (AGFI) was .96; and Comparative fit index (CFI) was 1.00 (indices exceeding .90 indicate acceptable fit). Examination of the direct effects showed that perceived social support and sense of mastery are negatively associated with symptom severity (-.19 and -.66 respectively). Additionally, perceived social support was positively associated with mastery (.30). Both mastery and social support were moderately related to quality of life (.46 and .53, respectively). Rmediation analysis revealed perceived social support and mastery fully mediate the relationship between symptom severity and quality of life. Additionally, mastery partially mediated the relationship between social support and quality of life. These findings highlight the importance of incorporating these psychosocial factors into clinical interventions with hopes of increasing levels of perceived social support and mastery, and ultimately promoting quality of life. Further research is needed to explore the best strategies to increase support and mastery within the brain injury population and to identify additional psychosocial factors that may be mediators of quality of life. M.S. in Psychology, July 2017 Show less