In the literature on firms and organizations, in economics, sociology, and business studies, there has been an increasing awareness that firms need others, outside the firm, in order to function, and particularly in order to innovate. This has led to the proliferation of studies on subjects such as outsourcing, inter-firm alliances, and networks of firms. Still, though, most of these studies focus on dyads of firms (i.e., strategic interaction of firms). Even in network studies, networks were seen mostly as aggregates of dyads. In contrast, in network analysis in sociology there has been, for some time, attention to roles and effects of third parties and of triads. In particular, the work of Ronald Burt (e.g. Burt, 1992) noted the importance, especially in the context of the acquisition of new information, of being a third party in ‘bridging structural holes’ between unconnected nodes or networks, and the opportunities for advantage as a tertius gaudens (laughing third) in playing agents off against each other. While in network analysis this attention to triads is relatively new, it has, in fact, a long history, going back, in particular, to the work of the sociologist Georg Simmel. A recent publication that acknowledges this is Krackhardt (1999).