Data are limited about the role of initiators in the transition to injection drug use. We examined the prevalence and predictors of giving someone their first injection using baseline data from a study involving 98 injection drug users (IDUs) in Toronto, Canada. Participants were recruited in 2011 using respondent-driven sampling. Findings revealed that 27.4 % (95 % CI 14.7–42.2) of IDUs had ever given anyone their first injection. In the logistic regression analysis, being unemployed and having ever spoken positively about injecting to a non-injector were associated with giving someone their first injection. Furthermore, the odds of initiating non-IDUs increased with the number of years that IDUs had been injecting. Our results provide support for interventions that aim to reduce the initiation of non-IDUs; however, further research is needed to shed light on the link between unemployment and initiation of non-injectors.