The aim of this research is investigating the role of personality types in predicting happiness, commitment and identity styles in university students in Islamic Azad University, Roudehen branch. The method of this research was correlational. With use of cluster random sampling one faculty between the faculties of university were chosen and 280 participants with simple random sampling attended to research and performed the inventories. Entrance criteria for participant include: undergraduate students in Educational courses, having psychological and physical health by self-report. The scales of this research were Framingham and burtner personality type’s inventory, oxford happiness inventory and bursensky identity styles inventory. The data were analyzed with Pearson correlation and multiple regression statistical methods. The results indicated B personality types can predict happiness and normative identity styles and a personality types can predict avoidant/diffusive identity styles.