The primary aim of this study was to provide an assessment of the current prevalence rates of International Classification of Diseases (11th rev.) posttraumatic stress disorder (PTSD) and complex PTSD (CPTSD) among the adult population of the United States and to identify characteristics and correlates associated with each disorder. A total of 7.2% of the sample met criteria for either PTSD or CPTSD, and the prevalence rates were 3.4% for PTSD and 3.8% for CPTSD. Women were more likely than men to meet criteria for both PTSD and CPTSD. Cumulative adulthood trauma was associated with both PTSD and CPTSD; however, cumulative childhood trauma was more strongly associated with CPTSD than PTSD. Among traumatic stressors occurring in childhood, sexual and physical abuse by caregivers were identified as events associated with risk for CPTSD, whereas sexual assault by noncaregivers and abduction were risk factors for PTSD. Adverse childhood events were associated with both PTSD and CPTSD, and equally so. Individuals with CPTSD reported substantially higher psychiatric burden and lower levels of psychological well-being compared to those with PTSD and those with neither diagnosis.