Non-suicidal self-injury (NSSI) is highly prevalent during late adolescence and young adulthood. There is some evidence of a link between NSSI and Borderline Personality Disorder (BPD), but little is known about the association between BPD traits and the various functions that maintain NSSI. The main purpose of this study was to explore the association between borderline personality traits and NSSI functions in a sample of college students. We also compared NSSI functions in college students who engaged in NSSI to those in an age-matched sample of BPD patients. This study included a total of 238 college students and 36 BPD patients. Participants were asked to complete a number of clinical measures. In the non-clinical sample, BPD features were more pronounced in the presence of NSSI, and we observed a differential relationship between NSSI functions and psychopathological BPD-traits. The NSSI clinical variables most strongly associated with BPD were frequency, variety of methods and severity, but not age of onset. Our results provide new information on the relationship between BPD and NSSI in young adults, and could be used to improve the early detection of vulnerable BPD-individuals and in planning NSSI treatment.