The interpersonal-psychological theory of suicidal behavior (Joiner, 2005) holds that an individual will die by suicide if he or she has both the desire for suicide and capability to act on that desire. According to the theory, suicidal desire results from the convergence of two interpersonal states: perceived burdensomeness and thwarted belongingness. However, desire alone is not sufficient to result in death by suicide--a third component must be present: the acquired capability for suicide, which develops from repeated exposure and habituation to painful and provocative events. The purpose of this article is to discuss four viable and timely directions for future research, given the current status of the theory.