Joiner’s (2005) interpersonal-psychological theory of suicide hypothesizes that painful and provocative events increase pain tolerance. The theory further proposes that increased pain tolerance represents one component of increased suicidal capability. Although initial studies have been consistent with this model, several key aspects remain untested. In 67 undergraduates, we investigated associations among painful and provocative events, nonsuicidal self-injury, acquired capability for suicide, and pain tolerance, threshold, and perceived intensity. Results were highly consistent with the interpersonal-psychological theory: a multiple mediation model specified that pain tolerance – but not other pain variables – accounted for significant variance within the association between painful and provocative events and acquired capability for suicide. These results held even when the pain tolerance item was removed from the suicidal capability questionnaire. Results also supported the interpersonal-psychological theory hypothesis that nonsuicidal self-injury represents an important painful and provocative event that increases suicidal capability. Specifically, participants with a history of nonsuicidal self-injury displayed increased suicidal capability and decreased pain perception. Overall, these results indicate that pain tolerance plays an important and specific role in suicidal capability.