The purpose of this study was to validate the Iranian version of the Identity Style Inventory (ISI). Participants were 376 (42% males) university students. Confirmatory factor analyses revealed a clear three-factor structure of identity style and a mono-factor structure of commitment in the overall sample as well as in gender subgroups. Convergent validity was demonstrated by theoretically consistent associations between the ISI factors and dimensions of psychological well-being. These findings suggest that the Iranian version of the ISI is a promising tool for evaluating social-cognitive processes that underpin the dynamics of identity formation in Iranian university students. (Contains 4 tables and 2 figures.)