Issues of regional innovation and learning have attracted growing interest from economic geographers and related specialists in recent years. The advantages to be gained from localised networks and learning are claimed to be particularly important for small and medium-sized enterprises (SMEs) in helping offset the size-related advantages of larger firms. Such claims are part of a wider rediscovery of the benefits of clustering and agglomeration in economic geography. Yet, to date, theoretical speculation about the renewed importance of geographical clustering for SMEs has run ahead of detailed empirical research. Beyond a few well-known case studies of high-technology clusters, there have been few attempts systematically to 'test' assertions made about the links between innovation, collaboration, and learning. The authors' purpose in this paper is to contribute new empirical evidence to this debate through a case study of SMEs in the Aberdeen oil complex. Although they find some evidence to support the role of localised forms of collaboration among the most innovative SMEs, the authors' results also indicate the importance of extralocal networks of knowledge transfer and the unequal power relations that underpin interfirm relations. These findings reinforce recent calls for a shift of focus from 'regions' to 'networks, raising some fundamental questions about the substantive basis of clusters policy.