What counts as a drug problem? What exactly is addiction? How big is the addiction ‘problem’? Researchers work in a wide range of disciplines to answer these questions, often relying upon information collected via screening and diagnostic tools (e.g., the four-item CAGE questionnaire or the ten-item AUDIT). Typically developed within epidemiological research, these tools establish and stabilise key criteria for identifying problematic substance use and addiction, and these criteria are then deployed to measure the extent and scale of the problems within populations. SSAC researchers Dr Robyn Dwyer and Professor Suzanne Fraser are currently examining the logics and assumptions at work within addiction screening and diagnostic tools. Along with many scholars who recognise that research methods actively constitute their objects of study, they ask how the tools define and shape the phenomena they purport to track. As Dr Dwyer explained, ‘our aim is to explore how these tools, and the ways they are used, actually make particular realities of addiction, and to ask whether and how different approaches, different tools, could make addiction differently – or even unmake it.’ In a recently completed analysis, Dr Dwyer and Professor Fraser identified three key processes, reduction, expression and quantification, through which addiction screening and diagnostic tools work to establish, standardise and reify addiction. They argue that together these processes locate addiction as an affliction of individuals, and they do this in part because it allows easy measurement. This work has been written up as a refereed journal article currently in peer review. Addiction screening and diagnostic tools are an important element in the expert knowledge-making through which the disease of addiction is materialised. The tools are promoted as objective and reliable and legitimated via statistical validation techniques. In the next phase of the project, Dr Dwyer and Professor Fraser will critically examine the validity claims made about addiction screening and diagnostic tools.