In this chapter, I focus on exchange in order to argue that illicit drug marketplaces are produced and reproduced through complex and dynamic social processes and relations. This understanding contrasts with dominant conceptions of drug (and other) markets that view them as driven by the mechanism of supply and demand, that largely ignore their constituent social relations and that tend to reify the ‘market’ as an object to be measured rather than a process to be understood. The chapter also challenges dominant and stigmatising constructions of heroin users and sellers (hereafter ‘dealers’) as denigrated, abject ‘others’, revealing that, in their everyday lives, they engage in similar practices and struggle with many of the same challenges as do we all.