Immunisation coverage in NZ was traditionally poor but has improved recently, with most children receiving their first vaccination on time. However, timely completion of vaccinations is still problematic - particularly for infants, often Maori, from lower income backgrounds. Research indicates that optimised systems in general practice can result in timely immunisation and reach national targets, even in practices where many patients are poor and living in remote areas. This project aims to apply the knowledge gained from practices who maintain high immunisation coverage to practices with the lowest immunisation coverage. We will use a randomised, controlled trial methodology to evaluate a recently developed model of Best Practice and compare the immunisation outcomes at six and eight months of age. The model of Best Practice has the potential to ensure the new immunisation health targets are met as well as reduce inequities in immunisation coverage, particularly for Maori.