The present study examined the temporal relationship between posttraumatic stress disorder (PTSD) and social support among 128 male veterans treated for chronic PTSD. Level of perceived interpersonal support and stressors were assessed at two time points (6 months apart) for four different potential sources of support: spouse, relatives, nonveteran friends, and veteran peers. Veteran peers provided relatively high perceived support and little interpersonal stress. Spouses were seen as both interpersonal resources and sources of interpersonal stress. More severe PTSD symptoms at Time 1 predicted greater erosion in perceived support from nonveteran friends, but not from relatives. Contrary to expectations, initial levels of perceived support and stressors did not predict the course of chronic PTSD symptoms.