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.