This review discusses selected neurobiologic and genetic factors-including noradrenergic and hypothalamic-pituitary-adrenal axis markers, oxytocin pathways, and serotonin transporter and brain-derived neurotrophic factor gene polymorphisms-in the context of resilience to stress, with an emphasis on social support. Social support's impact on medical and psychiatric health outcomes is reviewed, and putative mediators are discussed. The reviewed literature indicates that social support is exceptionally important to maintaining good physical and psychological health in the presence of genetic, developmental, and other environmental risks. Future studies should continue to explore the neurobiologic factors associated with social support's contribution to stress resilience.