The extent to which a specific negative life event (NLE) is a triggering factor for a suicide attempt is unknown. The current study used a case-crossover design, an innovative within-subjects design, to quantify the unique effects of recent NLEs on suicide attempts. In an adult sample of 110 recent suicide attempters, a timeline follow-back methodology was used to assess NLEs within the 48 hours prior to the suicide attempt. Results indicated that individuals were at increased odds of attempting suicide soon after experiencing a NLE and that this effect was driven by the presence of an interpersonal NLE, particularly those involving a romantic partner. Moreover, the relation between interpersonal NLEs and suicide attempts was moderated by current suicide planning. Interpersonal NLEs served as triggers for suicide attempts only among patients who were not currently planning their attempt. Findings suggest the importance of considering potential interpersonal NLEs when evaluating imminent risk for suicide attempts.