Research has suggested that social support can shape posttraumatic cognitions and PTSD. However, research has yet to compare the influence of separate domains of support on posttraumatic cognitions. Multiple-group path analysis was used to examine a model in a sample of 170 victims of intimate partner violence and 208 motor vehicle accident victims in which support from friends, family, and a close other were each predicted to influence posttraumatic cognitions, which were in turn predicted to influence PTSD. Analyses revealed that support from family and friends were each negatively correlated with posttraumatic cognitions, which in turn were positively associated with PTSD. Social support from a close other was not associated with posttraumatic cognitions. No significant differences in the model were found between trauma groups. Findings identify which relationships are likely to influence posttraumatic cognitions and are discussed with regard to interpersonal processes in the development and maintenance of PTSD.