Healthcare professionals must work together effectively in teams to provide the best possible patient care. However, previous research shows such multi-professional teams often fail to perform to their full potential, as they are not clear about their objectives, disagree about goals, their leadership and how to work together; or they find themselves trying unsuccessfully to meet the conflicting demands of senior managers from different disciplines and departments. The Healthcare Commission has discovered that as many as half of all NHS staff may work in dysfunctional teams which jeopardise patient care and staff well-being. The overall aim of this research is to discover how we can best promote and sustain effective multi-professional team working that delivers high quality healthcare and improves health outcomes for patients, users and carers.We will examine a wide variety of factors that affect the performance of healthcare teams by focusing on multi-professional team working for two priority groups: adults and older adults with mental health problems. We will involve service users, carers and a wide variety of stakeholders in determining what constitutes effectiveness.Through combining this approach with rigorous measures developed in previous research, we will identify ways of ensuring integration between diverse groups of professionals; effective working between the different teams that contribute to care of patients (hugely important from the perspective of users and carers concerned with continuity of care); systems to ensure that teams naturally and regularly review and improve their performance; and discover how to improve the organisation, management and leadership of services in order to dramatically improve team working and therefore patient care.Our aim is to develop effective methods of promoting multi-professional team working that can be applied across the whole of the NHS in order to significantly improve the productivity and effectiveness of our health and social care services.