Three studies tested a novel model of the narcissism-paranoia link, whereby narcissism (primarily its socially maladaptive facets) is associated with paranoia via over-use of defensive self-protection and/or under-use of self-affirmation. In Study 1, 245 online volunteers (87% female; MAGE =20.92; 44% White-British) completed trait measures of narcissism, self-enhancement/protection strategies and paranoia. In Study 2, 116 students (82% female; MAGE =20.23; 70% White-British) completed baseline measures, then reported state reactions and paranoia following two difficult and two pleasant interpersonal events after 3-10days. In Study 3, 517 online volunteers (64% female; MAGE =22.76; 77% White/Caucasian) completed baseline measures, experienced a standardized social exclusion (vs. neutral) manipulation (Cyberball), then reported state reactions and paranoia. In Study 1, narcissism was associated with higher paranoia via defensiveness. In Study 2, this was replicated in difficult but not pleasant events, and was driven by the Entitlement/Exploitativeness facet of narcissism. In Study 3, narcissistic rivalry and vulnerable narcissism, but not admiration, were associated with Cyberball-related paranoia via general defensiveness and denigration of others. Individuals high in narcissism-especially its socially maladaptive facets-who over-rely on defensive self-protection strategies in response to threat, are particularly vulnerable to paranoia. Findings help to understand individual differences in paranoia.