Structural equation analyses were used to examine the impact of social support vs. social undermining (conflict) on mental health in longitudinal data from 1,087 recently unemployed respondents. The results demonstrated that social support and social undermining were not the opposite poles of the same factor, each having some impact independent of the other. Social undermining had statistically significant and strong adverse impact at each concurrent level of mental health. It also predicted improvement (but not a high level) in mental health in subsequent time waves. In contrast, social support had a significant beneficial impact on mental health only at Time 1. Compared with the volatile and extreme effects of social undermining, those of social support appear weaker but more stable. These findings are consistent with literature on the impact of life events (S. E. Taylor, 1991) and on marital interactions and satisfaction (J. M. Gottman & L. J. Krokoff, 1989).