Perfectionism is highly and increasingly prevalent and is associated with concerning outcomes, including risk factors for suicidal ideation. However, it is not yet known under what conditions or through what mechanism perfectionism comes to be particularly maladaptive. Self-discrepancy theory suggests that perfectionism may be more maladaptive in the context of negative life events, through a pathway of appraisals of falling short of standards; this remains unstudied. To test this model, perfectionism, negative life events, appraisals, and demoralization were measured in a sample of 320 participants. The mediational pathway was supported, and perfectionism presented as a robust risk factor for both demoralization and appraisals of falling short of standards regardless of experience of recent negative life events. Indeed, perfectionism contributed far more variance to demoralization than this well-established risk factor. These results have clinical implications, in that perfectionism may meaningfully influence mental health outcomes even in the absence of activating life stressors, and this pathway may benefit from cognitive intervention. This study builds on extant literature to reveal an important mechanism by which perfectionism may lead to concerning outcomes, and establishes perfectionism as a consequential vulnerability factor independent of, and even relative to, negative life events.