The most commonly accepted view internationally is that addiction is an individualised brain-based disease or disorder. This view is buttressed by neuroscientific evidence, which is interpreted as demonstrating that the addicted brain undergoes long-term structural and functional changes as a result of substance use. Proponents of this model argue that such evidence is conclusive and that we have finally, over many decades, arrived at an enlightened, evidence-based, scientific understanding of addiction and dispensed with outdated ‘moral models’. However, critical scholars have argued that what we mean by addiction very much depends on the political–economic and socio-culture structure of a particular society at a particular temporal juncture. This paper seeks to build on this critical scholarship by examining shifting addiction understandings across time in Ireland. (This refers to the 26 counties of the southern Irish state.) This has involved analysing various documents, archives, and journal articles relating to the main ‘claim-making’ groups in Irish society (Catholic Church, medical profession, government, and media). It is argued that understandings of addiction through time in Ireland have tracked the country’s political–economic and socio-cultural development and have not developed according to ‘objective evidenced-based Science’. Furthermore, the portrayal of addiction across time has directed attention inwards to the diseased or disordered individual and away from macro-level processes. This has also led to the neglect of potentially vital areas of inquiry in relation to addiction scholarship in Ireland. To this end, the present research paper intends to highlight some of these macro-level processes in order to suggest fruitful avenues for future research