The present study contrasted the widely cited "buffer" model of social support with an alternative mediator model. Distinctions were drawn between the functions of social support under chronic vs. acute stress conditions, and between situation-specific stressors and major life events. Ongoing parenting stress was assessed in 96 mothers of deaf children and 118 matched controls. Tests of the competing models showed no moderating effects for social support. However, path analyses suggested that social support mediated the relationship between stressors and outcomes. Chronic parenting stress was associated with lowered perceptions of emotional support, and greater symptoms of depression and anxiety. Furthermore, parenting stress accounted for a substantial proportion of the variance in psychological distress scores in contrast to life event stress, which was only weakly related to psychological outcomes. The implications of mediational models for understanding adaptation to chronic stress are discussed.