The Big FIVE Inventory (BFI) is one of the most widely used personality questionnaires, but very few studies have been conducted on its psychometric properties in Iranian population. This study was carried out with the aim of studying the psychometric properties of the BFI questionnaire. For this purpose, 390 university students in Tehran (210 girls and 180 boys) with an age range of 18 to 56 years (M = 27.52; SD = 8.79) were selected using the convenience sampling method and completed BFI and NEO-FFI questionnaires. Cronbach's alpha, multitrait-multimethod matrix, and confirmatory factor analysis were used to estimate the psychometric properties of the questionnaire. The result of the confirmatory factor analysis showed that 15 of the 44 items did not have a strong factor loading (higher than 0.40) on the corresponding factors and were therefore removed from the questionnaire. The fit indices showed that the Persian version of 29 questions (BFI-29) with 5 factors has a good fit with the data. The reliability analysis also showed that the range of Cronbach's alpha coefficients of the factors is from 0.70 to 0.79. The lowest Cronbach's alpha coefficient was related to agreeableness factor and the highest was related to conscientiousness. The findings from the multitrait-multimethod matrix showed that the BFI-29 questionnaire has good convergent and divergent validity with the NEO-FFI questionnaire. In general, based on the results of the present study, it can be said that the BFI-29 questionnaire has desirable psychometric properties and whenever a short tool for personality measurement is needed, this questionnaire can be used.

The aim of the study was to examine the relationships between the FIVE factor MODEL (FFM) personality traits and identity styles. The sample (N= 359; 177 females and 182 males) was chosen through multi-stage stratified random sampling procedures from the population of undergraduate students from two large governmental universities in the city of Tehran. The FIVE factors of personality were assessed with the revised NEO personality inventory and three identity styles were assessed with the identity styles inventory (ISI). On the basis of correlation analysis, extraversion, agreeableness and conscientiousness were positively related to informational and normative identity styles. Openness was positively related to informational identity style and negatively related to normative identity style. In addition, neuroticism was negatively associated with informational and normative identity styles and positively associated with diffuse/avoidant identity style.Regression analysis showed that informational identity style was predicted by conscientiousness and openness. Normative identity style was predicted by conscientiousness, extraversion and agreeableness and negatively predicted by openness. Finally, diffuse/ avoidant identity style was negatively predicted by conscientiousness.