It takes time for both individuals and a field of endeavour to acquire the necessary knowledge and skills. In this chapter, we consider how such expertise develops, is maintained and expands. In the previous chapter, 'Making sense of complex dynamic spaces: The wicked problem of doping control in sport', we presented an overview of global efforts to address the persistent problem of the use of performance enhancing substances and techniques in sport. In this chapter, we focus on the work of anti-doping scientists. We use the Communities of Practice framework presented in the first Section this book to gain deeper insights into this process than we would otherwise.