Much scientific activity today is based on interdisciplinary collaborations in which multiple scientists with different areas of expertise share and integrate their cognitive resources in producing new results that cut across disciplinary boundaries. In this chapter, focus will be on how scientists involved in interdisciplinary collaborations link concepts originating in different disciplines or research fields and develop new concepts that cut across disciplinary boundaries. In recent publications, Collins, Gorman and others (Collins & Evans 2002; Collins, Evans, & Gorman, 2006; Gorman 2010) have argued that interdisciplinary collaborations can be analysed as trading zones varying along two different dimensions: a cultural dimension according to the degree of linguistic homogeneity or heterogeneity, and a power dimension according to the degree to which power is used to enforce the collaboration. On their account, only some trading zones, what they call inter-language trading zones, result in a truly merged culture in which a full blown creole language is the ideal end process. Other forms of trading zones are the enforced trading zone in which the expertise of an elite group is black-boxed for other participants, the subversive trading zone where one language overwhelms that of the other, and the fractionated trading zone which may either be a boundary object trading zone mediated by material culture of an interactional expertise trading zone mediated by language. Based on this typology, Collins et al (2006) have argued that interactional expertise trading zones are the norm for much new interdisciplinary work and that it will usually be the first step before an inter-language trading zone develops. Thus, a common developmental pattern will start from a heterogeneous collaboration, and as members of the trading zone become more interested in each other’s work they will develop interactional expertise, that is, sufficient mutual knowledge of each other’s fields to be able to interact in interesting ways, but without possessing the contributory expertise necessary to make original contributions outside of one’s own field. As collaboration intensifies, cultural differences will be reduced and the fractionated trading zone gradually transforms into an inter-language trading zone. However, this analysis exclusively focuses on how a collaboration may move between different kinds of trading zones over time, while it provides no answer to the question of how in detail “trading partners hammer out local coordination” (cf. Collins et al., 2006, p. 658). In order to answer this question several issues need to be addressed, among them, first, how scientists with different areas of expertise combine their cognitive resources, and second, how they come to agree on conceptual changes in overlapping areas. The rest of this chapter will be focused on these questions. First, I shall provide an account of conceptual development within a community. Second, based on this account I shall then describe how concepts from different disciplines may be linked or in other ways combined. In my analysis of how cognitive resources are combined I shall draw both on work in distributed cognition on the interlocking of mental models and on work in social epistemology on mutual trust and joint accept in groups.