In this chapter, we examine the global diffusion of evidence-based practice (EBP) beginning with its development in the USA and continuing with its translation to international contexts. The theory of technology diffusion and adoption, as well as actor network theory used in Chapter 5, arise from the field of science and technology studies (STS). Beginning in the 1960s, diffusion theory seeks to explain the way in which technology is transferred and communicated outwards through social systems – or networks – in the belief that it is only a matter of time before it is adopted. The pace of diffusion is said to depend upon the innovation’s perceived advantages, compatibility and comprehensibility, as well as the efficiency of the communication channels and information technology. Actor network theory, however, challenges the idea that innovations, such as evidence-based practice, and the technologies which support it, are stable entities that are passed from person to person – or group to group – through a process of diffusion. In diffusion theory, technologies are seen as independent of the different people – or systems – between which they are transferred. By way of contrast, actor network theory, influenced by Foucault’s relational perspective linking space and networks, sees technology – machines – as an important actor or actant in a network, which, through a process of translation by actors, is either sustained or challenged by the network. It studies how networks evolve, how actors become enrolled (or do not) in processes and make alliances (or do not) with other actors in an attempt to ensure that particular depictions of ‘progress’ prevail (Davies 2002: 196). Both theories offer analytical frameworks for studying the way in which evidence-based practice arises and is adopted – or is not – by the social work fraternity. And they complement one another in the sense that actor network theory adds to diffusion theory explanations of the communication channels that enhance or obstruct translation, or diffusion and adoption, as the case may be. In other words, actor network theory seeks to show how pivotal actors – and nodes of networks – ‘make sense’ or ‘nonsense’ – of a new innovation in the process of promoting or obstructing its translation into practice.