There is growing interest in understanding the fluctuations in grandiose and vulnerable narcissistic states over time. Momentary data collection is vital in facilitating this new area of inquiry. Two narcissism adjective scales, the Narcissistic Grandiosity Scale and the Narcissistic Vulnerability Scale, have recently been developed for this purpose. In the present study, the validity of these 2 scales was examined across 3 different samples. Results indicate that these measures perform well psychometrically at both the momentary- and trait-level. Multilevel exploratory factor analyses reveal a clear 2-factor structure at both the within- and between-person level. Within-person correlations between these scales and other momentary scales (e.g., the Positive and Negative Affect Schedule) are consistent with theoretical expectations. Finally, individual differences in endorsement of both of these scales correlated with other dispositional measures, including existing narcissism measures (e.g., The Pathological Narcissism Inventory and The Five Factor Narcissism Inventory), at the between-person level in the expected manner. We conclude these scales are well-suited for momentary narcissism assessment in studies wishing to examine fluctuations in grandiosity and vulnerability. (PsycINFO Database Record (c) 2019 APA, all rights reserved).