Narcissism is a relatively stable personality trait, which is most accurately described by three facets: agentic, antagonistic, and neurotic. Existing studies support the central role of antagonistic narcissism and its role in explaining the process of fluctuation in narcissism. However, there is a lack of a suitable adjective-based measure of antagonistic narcissism, resulting in intensive longitudinal studies assessing only agentic and neurotic narcissism. To address this gap and to advance research on fluctuations in narcissism, this article introduces the Narcissistic Antagonism Scale (NAS). Across six studies (total