It is common today to consider that knowledge creation is the basis of economic growth for a firm (Nonaka and Takeuchi 1995) or that learning regions (Florida 1995) or regional innovation systems (Cooke, Gomez Uranga, and Etxebarria 1997) are the basis for regional competitiveness. This regional competitiveness is due to the synergistic interaction between individuals and resources and has been discussed in terms of geographic clusters, industrial districts or tourism destinations (Hjalager 2000, 2010). However, it is less clear as to how and why innovation, creativity or synergy should be enhanced in a geographically constrained area although most recently there has been an emphasis on the importance of collaborative social interaction as a major factor in explaining this phenomenon. A large and growing body of empirical research shows that social relationships and the networks these relationships constitute are influential in explaining the processes of knowledge creation, diffusion, absorption, and use (Phelps, Heidl and Wadhwa 2012). This chapter examines these issues from the perspective of network theory leading to a focus on ‘knowledge networks’ research (Phelps et al. 2012). The study of knowledge networks incorporates a series of theories that have in common the idea that knowledge is searched for, created and transmitted through a set of nodes (which are individuals or higher level collectives that serve as heterogeneously distributed repositories of knowledge). The connections or relationships between these nodes enable and constrain the efforts of the nodes to acquire, transfer, and create knowledge (Phelps et al. 2012). This chapter will provide a brief introduction to the basics of the theory of networks and then diffusion theory that utilizes this network thinking. It identifies the importance of knowledge domains – key needs and uses for knowledge and how these constitute distinct networks of stakeholders. This chapter will then examine the knowledge domain networks in tourism: destination policy, infrastructure planning, destination marketing, and destination management networks.