Background: The aim of this study was to analyse whether narcissistic facets and indicators of the need for social validation predict behaviours related to ‘selfie’ addiction among students at the Autonomous University of Zacatecas (UAZ), Mexico, using a preliminary, adapted version of the NPI-40. Methods: An empirical, cross-sectional, non-experimental, correlational-predictive study was conducted with 255 students aged between 14 and 23, selected via convenience sampling. The adjusted NPI-40, the Psychometric Scale on Selfie Addiction, and six indicators of social validation and Instagram usage were employed. The data were analysed using exploratory factor analysis with a polychoric matrix and hierarchical linear regression. Results: The results revealed a preliminary structure comprising three factors and two observed composites of the adjusted NPI-40: authority, agentic grandiosity, exploitation, vanity, and exhibitionism. Behaviours related to selfie addiction were primarily associated with exhibitionism, exploitation, frequency of posting on Instagram and sensitivity to negative comments. The final model explained 29.5% of the variance. Conclusions: It is concluded that the relationship between narcissism, social validation and selfie addiction is not homogeneous and should therefore be analysed by facets.