The current study explores the problem with the lack of measurement invariance for the Narcissistic Personality Inventory (NPI) by addressing two issues: conceptual heterogeneity of narcissism and methodological issues related to the binary character of data. We examine the measurement invariance of the 13-item version of the NPI in three populations in Japan, Poland and the UK. Analyses revealed that leadership/authority and grandiose exhibitionism dimensions of the NPI were cross-culturally invariant, while entitlement/exploitativeness was culturally specific. Therefore, we proposed NPI-9 as indicating scalar invariance, and we examined the pattern of correlations between NPI-9 and other variables across three countries. The results suggest that NPI-9 is valid brief scale measuring general levels of narcissism in cross-cultural studies, while the NPI-13 remains suitable for research within specific countries.