This chapter examines the association between nonsuicidal self-injury (NSSI) and suicidal thoughts and behaviors. The history of NSSI and its overlap with suicidal self-injury is presented to provide context for the need to differentiate the two behaviors. Although there is a clear distinction between NSSI and suicidal self-injury, they frequently co-occur. Theories for understanding the association between NSSI and suicide attempts are explored, including the possibility of third variables to explain the association, as well as the utility of gateway theories and theories of acquired capability. The chapter closes with a review of the predictors of suicide attempts and suicide risk among people who engage in NSSI.