Most individuals have few close friends, leading to potential isolation after a friend's death. Do social networks heal to fill the space left by the loss? We conduct such a study of self-healing and resilience in social networks. We compared de-identified, aggregate counts of monthly interactions in approximately 15,000 Facebook networks in which someone had died with similar friendship networks of living Facebook users. As expected, a substantial amount of social interaction was lost with the death of a friend. However, friends of the decedent immediately increased interactions with each other and maintained these added interactions for years after the loss. Through this, the social networks recovered approximately the same number of active connections that had been lost. Interactions between close friends of the decedent peaked immediately after the death and then reached stable levels after a year. Interactions between close friends of the decedent and acquaintances of the decedent stabilized sooner, within a few months. Networks of young adults, ages 18 to 24, were more likely to recover than all other age groups, but unexpected deaths resulted in larger increases in social interactions that did not differ by friends' ages. Suicides were associated with reduced social-network recovery.Most individuals have few close friends 1-3 , and close friends are key sources of support 4 . After the death of a friend, close-friend networks could dissolve or experience long-term impairment. Although theoretical models suggest that networks are often globally robust to random losses 5,6 , we have limited empirical foundation for models of resilience in human networks. There are currently no large-scale studies that evaluate recovery and resilience after deaths in friend groups.A friend group could compensate for a loss by strengthening or building new friendships within-network, potentially even returning to similar levels of connectivity and function after a death. Studies on crises document increases in social interactions 7-10 , and increases in support are thought to reduce the negative effects of the crises 7,11 . Similarly, many bereaved spouses increase contact with children and grandchildren 12 and, especially after long periods of caregiving over which social contact declined, increase their social activity and participation in community groups 13,14 . However, small studies also record that social support networks can collapse 15 or, compared with control groups, show no significant change in social support 16 in the months and years after a death. Notably, longitudinal studies on the effects of deaths on social interactions are rare because pre-bereavement data are uncommon 16 , especially among non-elderly samples. With time, most bereaved individuals seem to exhibit resilient psychological responses to grief and trauma 17,18 , but average, precise and long-term patterns of social support after a death are less well established.Recent research on social networks during crises has found that friend groups react...