Many researchers have identified impulsivity-related personality traits as correlates of and risk factors for nonsuicidal self-injury (NSSI). Using a longitudinal design, we tested the hypothesis that one such trait, negative urgency (the tendency to act rashly when distressed), predicts the onset of NSSI during the first year of college and a different trait, lack of perseverance (the disposition to fail to maintain focus on tasks that are difficult or boring), predicts the maintenance of NSSI during the first year of college. In a sample of n = 1,158 college women (mean age = 18.04, 95% of participants were 18 at Time 1), we found support for these hypotheses. Negative urgency, measured prior to college entry, predicted the onset of NSSI behavior across the first year of college (odds ratio = 1.58). Lack of perseverance predicted the maintenance of NSSI status across the first year of college, controlling for prior NSSI behavior (odds ratio = 1.73). These findings indicate that different impulsivity-related personality traits may play different roles in the risk process for NSSI.