Abstract
Dual Diagnosis is becoming a fashionable term to describe and demarcate groups of service users who have severe and enduring mental health problems and concurrently use substances. To date, the term has been used loosely creating problems of definition and targeting of services. It is argued that the problems with dual diagnosis do not end at this point with important philosophical considerations arising from the power of such terminology to construct versions of social reality. In this sense the adoption of the discourse of dual diagnosis can be seen as a feature of an increasing medicalisation of aspects of social activity. The evaluative framework provided by postmodern notions of medical dominance and the psychological complex are relied on to suggest that services aiming to meet the needs of such people operate, ultimately, in the arena of social control.