This paper explores the role of social identity threat in risk discourse in an infrastructure project, and the consequences risk discourse has for cooperation between stakeholders. We show that risks posed a threat to the identity of the project team, resulting in a discourse focused on attributing responsibility for risks to outsiders and that polarized their relations with stakeholders. Consequently, the project team tried to eliminate risk by withholding information from the stakeholders they regarded responsible for inflicting risks on the project. This exacerbated intergroup relations and led to conflict. Given that social identity processes affect the way stakeholders discuss and handle risks, these findings are relevant for the design of risk management systems in projects.