Osteoarthritis (OA) is a very common chronic condition, causing a significant health and social burden. Every year more than 5% of the total adult population =55 years will consult their general practitioner (GP) about OA. Overseas, it is known that management of OA is well short of best practice. In NZ, little is known about the how GPs actually manage people with OA across the long-term course of the disease. Further, we have poor information about the economic and social costs (such as employment, productivity, income and welfare effects), due to lack of knowledge of the early clinical course and management of OA. This study will investigate the primary care management of OA, the health and social economic costs of OA across the whole course of the disease, and the potential gains from improving the delivery of care for OA. This will inform GP practice and national health policy.