The literature on inter-professional working tends to be dominated by explanations for lack of progress rather than accounts of achievements. This paper develops two models, termed the optimistic and pessimistic models respectively, to understand the factors that may underpin different rates of interprofessional achievement. A case study of the Sedgefield Integrated Team in County Durham, UK is used to test out aspects of the models. It is concluded that the grounds for pessimism have been overstated and that the scope for professional integration is greater than tends to be assumed.