A number of studies have demonstrated that Early Intervention in Psychosis (EIP) services can produce improved outcomes for service users. However, the essential elements that produce these results remain elusive. This paper considers a number of hypotheses, with a particular focus on one service in the UK, which was designed according to policy guidance. It concludes that the structure of EIP services allows for the effective implementation of evidence based psychosocial interventions, which often fail to be implemented successfully within standard mental health services.