Non-suicidal self-injury (NSSI) has been tied to several forms of emotional and behavioral dysregulation in adolescence, with less attention paid to regulation of anger. Most assume that anger dysregulation leads to engagement in NSSI, rather than the reverse. However, it is plausible that NSSI compromises adolescents’ abilities to regulate their emotions, including anger, because it may reduce the development of alternative regulatory strategies and intensify negative emotions by reducing tolerance of distress. Using three waves of data from a sample of adolescents in 17 Swedish schools (n = 1,304 M age = 13.68, SD age = .67; 89% of Swedish origin; 58% girls), we examined the directionality of ties between NSSI and three forms of anger dysregulation: dysregulated expressions of anger, anger suppression, and low anger reflection. We also looked for differences in magnitude of paths and gender differences. Random-intercept cross-lagged panel models showed that NSSI predicted changes in all forms of anger dysregulation but found no support for the opposite direction. Gender differences were not evident. Results challenge directionality assumptions and support suggestions that adolescents’ anger regulation degrades when they self-injure.