Background Much of the psychosocial care people receive after major incidents and disasters is informal and is provided by families, friends, peer groups and wider social networks. Terrorist attacks have increased in recent years. Therefore, there is a need to better understand and facilitate the informal social support given to survivors. Aims We addressed three questions. First, what is the nature of any informal support-seeking and provision for people who experienced the 2017 Manchester Arena terrorist attack? Second, who provided support, and what makes it helpful? Third, to what extent do support groups based on shared experience of the attack operate as springboards to recovery? Method Semi-structured interviews were carried out with a purposive sample of 18 physically non-injured survivors of the Manchester Arena bombing, registered at the NHS Manchester Resilience Hub. Interview transcripts were thematically analysed. Results Participants often felt constrained from sharing their feelings with friends and families, who were perceived as unable to understand their experiences. They described a variety of forms of helpful informal social support, including social validation, which was a feature of support provided by others based on shared experience. For many participants, accessing groups based on shared experience was an important factor in their coping and recovery, and was a springboard to personal growth. Conclusions We recommend that people who respond to survivors’ psychosocial and mental healthcare needs after emergencies and major incidents should facilitate interventions for survivors and their social networks that maximise the benefits of shared experience and social validation.