Research has suggested that African American and Latinx adults may develop posttraumatic stress disorder (PTSD) at higher rates than White adults, and that the clinical course of PTSD in these minority groups is poor. Factors that may contribute to higher prevalence and poorer outcome in these groups are sociocultural factors and racial stressors, such as experiences with discrimination. To date, however, no research has explored the relationship between experiences with discrimination and risk for PTSD, and very little research has examined the course of illness for PTSD in African American and Latinx samples. The present study examined these variables in the only longitudinal clinical sample of 139 Latinx and 152 African American adults with anxiety disorders, the Harvard/Brown Anxiety Research Project-Phase II. Over 5 years of follow-up, remission rates for African Americans and Latinx adults with PTSD in this sample were 0.35 and 0.15, respectively, and reported frequency of experiences with discrimination significantly predicted PTSD diagnostic status in this sample, but did not predict any other anxiety or mood disorder. These findings demonstrate the chronic course of PTSD in African American and Latinx adults, and highlight the important role that racial and ethnic discrimination may play in the development of PTSD among these populations. Implications for an increased focus on these sociocultural stressors in the assessment and treatment of PTSD in African American and Latinx individuals are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).