General practitioners have always had special interests. Recent policy initiatives in the UK, organizational changes and changing attitudes by the Royal Colleges have meant that there is an increasing interest in the development of a new role for GPs with special interests (GPSIs). This paper considers what methodology is best suited to examining change, while that change is still developing. Specifically, it offers a model that identifies different forms of knowledge; anticipated, explicit and tacit and considers how these can combine in an evaluative model for innovations in primary care. The paper goes on to identify potential benefits and risks of a shift towards GPSIs. It develops a picture of GPSI services in one PCT and focuses on two disciplines, orthopaedic medicine and urology. Views of those GPs providing these services are reported and are linked with the possibilities that a new form of general practice might emerge without general practitioners.