Objective: While major theories of non-suicidal self-injury (NSSI) emphasize the behavior's role in emotion regulation, little is known about the daily emotional experiences of self-injurers. This study investigated the specific emotions that are characteristic of those who engage in NSSI. Method: University students (n = 84) with either no history or a recent history of NSSI completed daily diary and retrospective measures of emotional experience. To evaluate generalizability of findings, the retrospective measure was also administered to a diverse sample of U.S. adults (n = 92) with and without histories of NSSI. Results: Results indicate that self-injurers experience greater negative emotionality, particularly self-dissatisfaction, compared to individuals with no NSSI history. Self-injurers also reported less positive emotion, but these effects were smaller. The pattern of results was similar when controlling for Axis I psychopathology and borderline personality disorder symptoms. Conclusions: Individuals who engage in NSSI experience more negative emotions, generally, and more self-dissatisfaction, specifically. Findings contribute to the growing literature on the role of emotion in the etiology and functions of NSSI.