SummaryUnder standard care, psychotic disorders can have limited response to treatments, high rates of chronicity and disability, negative impacts on families, and wider social and economic costs. In an effort to improve early detection and care of individuals developing a psychotic illness, early intervention in psychosis services and early detection services have been set up in various countries since the 1980s. In April 2016, NHS England implemented a new ‘access and waiting times’ standard for early intervention in psychosis to extend the prevention of psychosis across England. Unfortunately, early intervention and early detection services are still not uniformly distributed in the UK, leaving gaps in service provision. The aim of this paper is to provide a business case model that can guide clinicians and services looking to set up or expand early detection services in their area. The paper also focuses on some existing models of care within the Pan-London Network for Psychosis Prevention teams.