Background: Self-injurious behavior (e.g., nonsuicidal self-injury, suicide attempts) is a serious public health concern. One potentially important but understudied predictor of nonsuicidal and suicidal self-injury involves the behavioral inhibition and activation system (BIS/BAS). Aims: The goal of the current study was to examine the relationship between nonsuicidal and suicidal self-injury and BIS/BAS, and to consider the influence of related variables in the relationship. Examination through this framework allowed us to consider BIS and BAS as potential unique risk factors of self-injury. Method: After examining the relationship between nonsuicidal and suicidal self-injury and BIS/BAS among 1,912 participants, we used propensity scores to match participants' propensity for nonsuicidal self-injury and suicide attempts based on demographic variables (e.g., gender, age) and related risk factors (e.g., anxiety, depressive symptomology, impulsivity, and substance use problems). Results: Participants who reported nonsuicidal self-injury or attempted suicide scored higher on BIS and BAS compared with those without a history of these behaviors. After matching procedures, however, the only group difference found was on BIS between those with and without a history of nonsuicidal self-injury. Conclusion: Results support the notion that the behavioral inhibition system might play a role in nonsuicidal self-injury but not in suicidal self-injury.