Objectives We examined links between marital quality and loneliness among aging veterans and explored whether veterans’ PTSD symptom severity moderated these associations. Methods Data came from 269 Vietnam-Era combat veterans who had a spouse/partner (M age = 60.50). Utilizing two waves of data spanning six years, we estimated multiple regression models that included positive and negative marital quality, PTSD symptom severity, and loneliness in 2010 as predictors of loneliness in 2016. Results Facets of positive (but not negative) marital quality were associated with veterans’ loneliness. Companionship – spousal affection and understanding – was associated with lower subsequent loneliness among veterans with low/moderate – but not high – PTSD symptom severity. Conversely, sociability – the degree to which one’s marriage promotes socializing with others – was associated with lower subsequent loneliness regardless of PTSD symptom severity. Conclusions Companionship and sociability were each associated with veterans’ subsequent loneliness. Whereas benefits of companionship were attenuated at higher levels of PTSD symptom severity, benefits of sociability were not.