This paper examines learning among museum staff involved in exhibition development in four European natural history museums. It draws upon a larger body of research1 undertaken for the Mirror project, a European Commission Framework Programme 5 Information Society Technologies (FT5 IST) project aimed at enhancing and improving co-operative practices through the use of new technologies. The aim of this paper is to characterize learning and co-operative practices derived from the interactions of highly heterogeneous teams involved in constructing museum exhibitions, and particularly to distinguish and examine the relationships between actions aimed at fulfilling team-focused exhibition outcomes and those which draw upon the knowledge base of external peer groups. The concepts of communities of practice (Wenger, 2000, Wenger, Snyder and McDermott, 2002), situated learning (Lave and Wenger, 1991) and vertical team-work and horizontal peer-group exchange are used to describe the learning interactions and co-operative practices. However, whilst the relationship between situated learning and Communities of Practice has determined our preliminary theoretical perspective, this has, as we explain below, been heuristically revised in the light of the practical reality that we encountered.