This paper provides a reflective account of the different disciplinary approaches to studying illicit drug markets. The term ‘drug market’ is used widely in illicit drug research, and means different things to different researchers. An economist may have a very specific view of what is meant by a drug market, and that will differ from one held by an ethnographer. The paper endeavours to describe and explain five different disciplinary approaches to studying drug markets—ethnographic and qualitative approaches, economic approaches, behavioural and psychological research, population-based and survey research, criminology and law enforcement evaluation. Each discipline has strengths and limitations. I do not argue for the supremacy of one approach, but that we need to appreciate the different approaches and develop better multi-disciplinary models.