This paper argues that the interfaces between formal and informal care-giving are changing as a result of two current trends; the increased scope of home-based nursing care and the emphasis on participation both within nursing and in the wider health and social care arenas. These various changes are explored in relation to the provision of intensive and complex nursing care in the home. It will be argued that the changing interfaces between formal and informal care have important implications for the respective roles of nurses and informal carers which hitherto have been relatively overlooked. These implications urgently need addressing in research, policy and public debate if professional nurses are to provide appropriate help and support to informal carers.