This research explores the understudied phenomenon of performance and image enhancing drug (PIED) markets by examining the structure and formation of the market for PIEDs in the Netherlands and Belgium. Furthermore, this study aims to understand and analyse the actors that operate in the PIED dealing environment. In particular bodybuilding is adopted as a case study. Finally, this thesis examines how the PIED control system and its application influence these respective markets. Chapter one introduces the global PIED problem, the policy options currently available to deal with it, and its connection to anti-doping and sport. Chapter two begins by reviewing the literature on PIED use and its supply, and reflects on the anti-doping and PIED policies that seek to regulate this market. In chapter three the theoretical contours of this dissertation are developed. Chapter four describes the research methods which form the empirical bases of the findings chapters. Chapter five focuses on the general characteristics of PIED suppliers, and the ways in which the actions of PIED dealers are influenced by the market cultures in which they operate. Chapter six examines the importance of socio-cultural factors in the formation and development of PIED dealing networks within bodybuilding subcultures. Chapter seven analyses and describes the characteristics of the Belgian and Dutch PIED markets, and unravels the complex relationship between the two. Chapter eight explores the illegal production of steroids in the Netherlands and the flourishing Internet trade in Belgium. Chapter nine assesses the harms related to the production and distribution of PIEDs, and accounts for the effects that Belgian and Dutch PIED policies may have on this illicit market. Finally, in chapter ten, the main findings of this dissertation are summarized, future research endeavours are considered and policy implications are drawn from the analysis. This thesis illustrates that social systems of rules and values, and in particular the embeddedness of ...