Introduction: The present study was an attempt to standardize and check the psychometric properties of Ego Identity Process Questionnaire among Iranian students.Method: Initially at pilot stage, 150 students of psychology at Shahid Beheshti University responded to the questionnaire, and after revision it was administered to 100 students who were selected using multi-stage cluster sampling.Results: Using confirmatory factor analysis, the eight factor structure was confirmed with 2 domains: ideological and interpersonal. However, the 2 factor structure of commitment and exploration was not confirmed. Using exploratory factor analysis, three factors were identified: commitment, lack of commitment, and discovery.Conclusion: The reliability and validity coefficients were generally satisfactory. Seven items were omitted from the questionnaire, and the resulted 25-item questionnaire formed a homogeneous collection that had a proper factorial structure and was qualified for being used in psychological research and clinical and diagnostic activities.