This paper examines young women's initiation to heroin use in the context of an intimate relationship based on data from a small-scale ethno-epidemiology of heroin use in Ireland, 2007–2009. The epidemiological sample included 120 young people, and life history interviews were conducted with a sub-sample of 40 youth aged 16–25 years. A detailed analysis of the “risk environment” of young women's heroin initiation highlights a complex interplay between women's agency and intimate partner influence. It is argued that dichotomous representations of women as victims or emancipated consumers do not adequately capture the complexity of women's initiation journeys. The study's limitations are noted and implications for drug use prevention and harm reduction strategies are discussed.