This article discusses a support group programme initiated in response to the Manchester Arena attack in 2017 as an example of a psychosocial approach to post-disaster support. Its purpose is to highlight how a bespoke psychosocial peer-based initiative can complement and enhance mental health responses following collective trauma events. It gives an overview of psychosocial approaches to disaster aftercare and presents survey-based and other feedback gathered throughout the life of the programme. The results suggest that facilitated peer support has enabled bereaved people, survivors and responders to share and make sense of their experiences, benefit from mutual support and enhance their coping and resilience. A multidimensional psychosocial approach to peer support has culminated in the development of a self-sustaining peer support network. The case study builds on the evidence base supporting the value of psychosocial approaches as an important complement to clinically focused mental health interventions following a collective trauma event.