BACKGROUND: The development of early intervention services for young people with first-episode psychosis is a priority internationally. AIMS: To evaluate the development, implementation and impact of existing and newly formed early intervention services in England. METHOD: Multiple-case study involving staff, users, carers and commissioners of 14 early intervention services. RESULTS: Service numbers increased in response to national policy directives. They were still actively working with 90.6% of service users 12 months after inception. They were highly valued by users and carers as providing a personal service that contrasted with previous experiences of care. Tensions between providing a quality service and meeting case-load targets linked to future funding led teams to adopt a series of survival strategies with some unintended consequences. CONCLUSIONS: Early intervention services are highly valued by consumers and engage users effectively after 12 months. Implementation of these services is threatened unless sufficient consistent funding is made available.