PTSD prevention requires attention to the risk and protective factors that influence its development following a traumatic event. Genetic predisposition is associated with long-term risk for mental illness, but both extrinsic resiliency factors, such as emotional support, and intrinsic resiliency factors, such as trait resilience, may be able to attenuate this risk. In a well-powered trauma-exposed civilian cohort, we seek to explore the relationships between genetic risk, resilience, and PTSD symptoms, applying racially-informed algorithms to more responsively study genetics in diverse samples. Polygenic risk algorithms from one previous genome-wide association study (GWAS) conducted in a European American sample and from one previous GWAS conducted in an African American sample were applied to participants according to self-reported race. Data from baseline, 2 weeks post-trauma, and at 3 months post-trauma were harmonized with genetic data and analyzed from 878 adult participants who initially arrived at the Emergency Department due to a traumatic event (African American cohort: n=578, European American cohort: n=300). We used linear regression models to test whether emotional support and trait resilience moderate the influence of genetic predisposition on PTSD development at 3 months following adulthood trauma. We conducted a principal component analysis and included the first 10 principal components as covariates in our models. All models were adjusted for trauma severity, age, and gender. When the appropriate polygenic risk algorithms were applied, we found a statistically significant protective association between genetic predisposition and PTSD symptoms in African American participants (β=-0.109, SE=0.003, p<0.01), invalidating previously proposed polygenic risk algorithms and illuminating a need to complete further research and improve genetic prediction models for racially-marginalized groups. However, we found a statistically significant relationship between polygenic risk and PTSD symptoms following traumatic exposure in European American participants (β=0.093, SE=0.004, p<0.01). Both emotional support and trait resilience were able to mitigate the influence of genetic predisposition on PTSD symptoms in trauma-exposed European Americans. The moderating capacity of resilience highlights an opportunity to introduce new population-wide preventative measures, including support groups, psycho-education campaigns, and resilience-building public policies.