Abstract: A higher prevalence of posttraumatic stress disorder (PTSD) among females has been consistently documented. For example, a nationally representative study of the US adult population found that the prevalence of lifetime PTSD was 8.0% in females and 4.1% in males. This difference is especially evident among military veterans, in whom experiences such as military sexual trauma (MST), which is more prevalent among females, may place female veterans at greater risk for PTSD. Despite considerable attention to this sex difference, however, scarce research has examined factors that may contribute to it. Sex differences in PTSD prevalence may be attributable to differences in trauma exposures (eg, adverse childhood experiences, sexual trauma), psychological traits (eg, resilience), and social factors (eg, loneliness). Here, we analyzed data from a nationally representative sample of US veterans to examine how a wide range of such factors might indirectly account for sex differences in PTSD.