The "PrimInject" online survey, which aimed to better understand the current circumstances surrounding a person’s first injection in France, provided an opportunity to collect accounts of how people began injecting during its first two months online. After excluding accounts concerning initiation prior to the year 2000, a corpus of 16 accounts was compiled. Based on an analysis of this corpus and drawing on other research, this article, which adopts a typological approach, proposes distinguishing four pathways into injection drug use. These pathways, as described by users, outline the various subjective dimensions within which initiation occurs and which provide the practical and symbolic “good reasons” for switching to injection: emotional regulation, social integration, relational engagement, and hedonism. [author’s abstract]