Both nonsuicidal self-injury (NSSI) and purging behaviour are thought to involve harm to the self. The acquired capability for self-harm model holds that engaging in one self-harming behaviour increases the capability to tolerate harm to the self, thus increasing risk for engaging on other such behaviours. In addition, both behaviours are thought to serve the similar function of relief from distress. We thus tested whether engagement in one of these behaviours predicts the subsequent onset of the other. In a longitudinal design, 1158 first-year college women were assessed for purging and NSSI at two time points. Engagement in NSSI at time 1 predicted the college onset of purging behaviour 9 months later (OR = 2.20, p < .04, CI = 1.07-4.19) beyond prediction from time 1 binge behaviour, and purging behaviour at time 1 predicted the subsequent onset of NSSI (OR = 6.54, p < .01, CI = 1.71-25.04). These findings are consistent with the acquired capability for harm model and with the possibility that the two behaviours serve a similar function.