A nationally representative sample of Norwegian high school students (ages 14 to 19, N = 2,924) completed self-reports in school about non-suicidal self-injury (NSSI), suicide attempt (SA), and risk and protective factors. They were re-examined 5 years later. In all 2.2% reported NSSI with no SA during the follow-up period and 3.2% reported SA. Several risk and protective factors were common to NSSI and SA: previous SA, young age, debut of sexual intercourse before the age of 15, and non-heterosexual sexual interest. However, other risk and protective factors were unique to NSSI or SA: Previous NSSI increased the risk for future NSSI whereas satisfaction with social support protected against later NSSI. Suicidal ideation increased the risk for SA whereas attachment to parents protected against it. NSSI did not increase the risk of future SA. NSSI and SA may be thus conceived of as only partly overlapping phenomena, and not necessarily just representing different degrees of suicidality.