Suicide is a leading cause of death. NHS workers, especially female nurses, have heightened vulnerability. Being impacted by a colleague's suicide can lead to increased suicidality. Postvention refers to support following a suicide. We investigated current, available postvention for NHS workers following a colleague's suicide and the experiences of staff who deliver it ("supporters"). Twenty-two supporters were interviewed, and data were analyzed using classic grounded theory. The theory of negotiating postvention situations was developed. Supporters must negotiate enabling and disabling elements that form a "postvention situation" and impact behaviors and postvention efficacy. Postvention delivery is emotionally burdensome. Supporters need support, which they do not always receive. Postvention can lead to learning, which can better inform future postvention. The extent to which NHS workers can effectively support colleagues will depend on their postvention situation. As such, work must be done to enable supporters to offer effective postvention in the future.Suicide; postvention; healthcare workers; grounded theory.