Purpose <p>This study examined the association between a child’s or adolescent’s witnessing or direct experience of interparental violence on the manifestation of post-traumatic stress symptoms (PTSS) in young adults in Taiwan. It then analyzed the role of social support as a mediator and gender as a moderator in this association.</p> Method <p>This was a cross-sectional study, carried out with 790 social work university students in Taiwan using a retrospective, self-administered questionnaire. We used sequential regression analyses to test the moderation hypotheses and an integrative structural equation modeling (SEM) approach to test the mediation hypotheses.</p> Results <p>The results of bi-variate analysis revealed significant relationships between <i>witnessing</i> interparental psychological and physical violence and directly <i>experiencing</i> psychological and physical violence. Findings also found significant relationships between exposure to family violence and PTSS symptoms. Gender had a significant moderating impact for females but not for males when assessing the association between witnessing and experiencing interparental physical violence and rates of PTSS (<i>β</i> = 0.05, <i>p</i> &lt;.001; <i>β</i> = 0.06, <i>p</i> &lt;.001; respectively); social support had a significant mediating effect on the relationship between experiencing parental violence during childhood/adolescence and current PTSS (standardized effect = 0.14, SE = 0.01, <i>p</i> &lt;.01, 95% CI [0.076, 0.249]).</p> Conclusion <p>The results of this study highlight the influential role that social support can play in the association between exposure to different types of family violence during childhood and mental health consequences during young adulthood.</p>