Background: By evaluating the psychometric properties of the Persian version of the Internet Addiction Test-Social Networking Sites version (IAT-SNS) in a sample of Iranian university students, this study investigated the dimensionality of SNS addiction for the first time. Methods: A total of 620 SNS users (414 women) participated in the study. The study questionnaire comprised demographic information, SNS usage patterns, the IAT-SNS, and the Bergen Social Media Addiction Scale (BSMAS). Findings: Exploratory factor analysis (EFA) identified the 3-factor structure of the IAT-SNS, namely ‘Lack of Control’, ‘Emotional and Relational Conflict’, and ‘Preference for online relationships’ that explained 54% of the total variance. Confirmatory factor analysis (CFA) verified the current model. Problematic users on average exhibited higher scores on the whole IAT-SNS and each of the 3 factors as compared to non-problematic users. The IAT-SNS and its factors showed good internal consistency, and strong convergent and concurrent validity. Conclusion: The Persian version of the IAT–SNS is valid and reliable, and is applicable for measuring the 3 dimensions of SNS addiction among students.