Ostracism-being excluded and ignored-has severe, negative consequences. What is less clear is why some individuals become frequent targets of ostracism in the first place. In two nationally representative panel surveys, one experience sampling study, and six experiments (Ntotal = 77,289), we examine associations between grandiose narcissism and ostracism. Cross-sectional panel data (Study 1) and a 14-day experience sampling study (Study 2) show a strong link between narcissism and reporting ostracism more frequently. Subsequent studies provide insight into three mechanisms underlying this relationship: First, experiments show that narcissists are more sensitive to ambiguous but not to unambiguous exclusion cues (negative perceptions mechanism; Studies 3a, 3b, and 3c; integrative data analysis; and Study 4). Second, other individuals exclude narcissists more often because of their narcissistic traits (target behavior mechanism, Studies 5 and 6). This holds true both when narcissistic traits, especially narcissistic rivalry, are explicitly described and when narcissistic traits are implicitly inferred from short introduction videos. Finally, Study 7 longitudinally tests over 14 years whether narcissism is an antecedent and outcome of frequent exclusion. Supporting a reverse causality mechanism, deviations in ostracism were followed by deviations in narcissism 1 year later, and vice versa. Our findings demonstrate how negative perceptions, target behavior, and reverse causality together determine who gets ostracized, from the perspective of those who get ostracized and those who decide to ostracize. We discuss how the present approach can be used as a framework to understand personality risk factors for frequent negative social experiences. (PsycInfo Database Record (c) 2025 APA, all rights reserved).