A pragmatic approach to those with a dual diagnosis of mental illness and problem drug use accepts that drug and alcohol use is firmly established in this population, and aims to minimise and reduce any harms associated with using. However, it is evident that we know little about drug using practices and knowledge among this group in order to effect such an approach. This paper aims to investigate the potential of utilising a harm reduction based approach as an alternative to current service responses for those with a dual diagnosis.