Some literature discusses the relative lack of theory in this area.  This applies both to different understandings of the relations between science and the societies in which it is practiced and developed - its purpose, leadership and accountability - and, more specifically, to the role of engagement work in such an environment.  It seems to this author that articulating the former contributes significantly to understanding the latter.  However, there are other difficulties in theorising 'engagement' which relate to the variety of purposes for which it can be intended. As we have argued elsewhere (see Purpose), there are a number of legitimate reasons for pursuing engagement, each of which imply a different process with a different set of people and may also possess a different theoretical rationale relating to different aspects of the research programme itself and the socio-political dynamics of the environment in which it is operating. It is therefore questionable as to whether a single theory of engagement is possible.