Attitudes towards the body have been largely overlooked as a potential risk factor for adolescent non-suicidal self-injury (NSSI) despite theorizing that a negative body image may play a critical role in the development of this behavior. The current study used structural equation modeling to evaluate the fit of a theoretical model specifying body image as a mediator between negative affect and NSSI in a combined clinical and non-clinical sample of 284 adolescents. The data supported the model, accounted for 21.6% of the variance in NSSI, and body image significantly mediated the relationship between negative affect and NSSI. These findings provide essential preliminary evidence that body image may represent a necessary but not sufficient risk factor for NSSI in adolescents and that treatment for NSSI should consider targeting body-related pathology in addition to emotion regulation. The findings also support including body image within developing etiological models of NSSI. (Contains 2 tables and 2 figures.)