The nature of the professional task in welfare services is constantly changing. These changes are not confined to Britain but are widespread across the developed world and include initiatives to develop new professional roles and redesign existing services. Central to these initiatives is an assumption that the professions, and the individual professionals involved, will be willing and able to adapt their professional practice. The challenges inevitably posed by these developments appear to have been played down, particularly in respect of the role played by the boundaries between professions. This article considers the nature of boundaries before exploring these service developments as a means to highlight the issues they raise. The article contends that for these developments to work we need to move beyond the current focus on the role of education, training and regulation which structure professional boundaries to appreciate the 'human and social aspects' of these changes in order to understand how individual professionals perceive and experience the boundaries between professional groups.