Across three studies, we examined the moderating effect of narcissistic vulnerability on the relationship between narcissistic grandiosity and persistence. In Study 1 (n = 338), narcissistic grandiosity predicted greater goal-drive persistence, but only when individuals also possessed a degree of narcissistic vulnerability. In Study 2 (n = 199), we replicated these effects and demonstrated that they were independent of socially desirable responding. In Study 3 (n = 372), narcissistic vulnerability moderated the grandiosity – persistence relationship to predict persistence for personally relevant goals and hypothetical goals. Notably, the moderating effect of vulnerability was independent of the effects of self-esteem. These results provide the first evidence that narcissistic grandiosity predicts persistence only in the presence of self-doubt regarding superiority. The results demonstrate the importance of considering the interplay between the two components of narcissism.