Aims To showhowthe inclusion of agent-based modelling improved the integration of ethno-epidemiological data in
a study of psychostimulant use and related harms among young Australians. Methods Agent-based modelling,
ethnographic fieldwork, in-depth interviews and epidemiological surveys. Setting Melbourne, Perth and Sydney,
Australia. Participants Club drug users in Melbourne, recreational drug users in Perth and street-based injecting
drug users in Sydney. Participantswere aged 18–30 years and reported monthly ormore frequent psychostimulant use.
Findings Agent-based modelling provided a specific focus for structured discussion about integrating ethnographic
and epidemiological methods and data. The modelling process was underpinned by collective and incremental design
principles, and produced ‘SimAmph’, a data-driven model of social and environmental agents and the relationships
between them. Using SimAmph, we were able to test the probable impact of ecstasy pill-testing on the prevalence of
harms—a potentially important tool for policy development. The study also navigated a range of challenges, including
the need to manage epistemological differences, changes in the collective design process and modelling focus, the
differences between injecting and non-injecting samples and concerns over the dissemination of modelling outcomes.
Conclusions Agent-based modelling was used to integrate ethno-epidemiological data on psychostimulant use, and
to test the probable impact of a specific intervention on the prevalence of drug-related harms. It also established a
framework for collaboration between research disciplines that emphasizes the synthesis of diverse data types in order
to generate new knowledge relevant to the reduction of drug-related harms.