The un is increasingly relying on private military and security companies (pmscs) for a wide range of services. Until recently, un use of pmscs was not governed by systemwide rules and standards. The establishment of guidelines on the use of armed private security in late 2012 has led to greater accountability and transparency around this practice. The guidelines clarify the decision-making process and the criteria for the selection and hiring of companies providing armed security. However, they are overly reliant on self-regulation by pmscs and remain limited, raising questions about their capacity to avoid companies with objectionable records and prevent potential incidents. Moreover, the guidelines raise concerns that the use of pmscs by the un may become normalised, with yet unexamined effects on the organisation’s security policies and its image.