Background: Young adult sexual minority women (SMW) are at elevated risk for sexual assault (SA), posttraumatic stress disorder (PTSD), and inadequate social support. While SA and PTSD can lead to reductions in social support from close significant others, the impact of SA and PTSD on SMWs' social support has not previously been assessed.Objective: This study examined the associations of past year SA and PTSD with SMW's social support from intimate partners, family, and friends. It was hypothesized that SA and PTSD would be negatively associated with support from partners, family and friends, and that PTSD would moderate the effect of SA on support in early adulthood.Method: Young adult SMW in the United States (N = 235) who were M = 23.93 (SD = 2.15) years old, primarily lesbian or bisexual (n = 186, 79.1%) and White (n = 176, 74.9%) completed measures on past year exposure to SA and non-SA trauma, PTSD, and social support from intimate partners, family and friends.Results: PTSD was associated with less social support from partners, (__-mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"-__b = -0.06, SE = 0.02, p = .010, R2change = .02), family, (__-mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"-__b = -0.06, SE = 0.03, p = .025, R2change = .02), and friends, (__-mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"-__b = -0.07, SE = 0.02, p = .008, R2change = .02). There was a significant interaction between PTSD and SA on social support from partners (__-mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"-__b = -0.01, SE = 0.01, p = .047, R2change = .01). Neither non-SA nor SA trauma was associated with support from family or friends.Conclusions: Results underscore the potential impact of recent SA on intimate partnerships for young adult SMW with more severe PTSD. Future work should explore how addressing PTSD and improving social support quality may help SMW recover from traumatic experiences and ameliorate the effects of SA on intimate partnerships.