The fact that childhood temperament is one of the most important determinants of adults' emotional and psychological disorders makes early assessment of difficult and problematic temperament necessary. Moreover, appropriate tools are needed to attain this objective. The present study seeks to evaluate the psychometric characteristics of ps-TCI in the Iranian preschoolers. A statistical sample of 200 children from five kindergartens in Shahriar was randomly selected through the process of cluster sampling, and their temperament and personality were tested by 18 kindergarten teachers using the Cloninger’s Preschool Temperament and Character Inventory. After fourteen days, the process was repeated, and its validity and reliability were assessed. The reliability was calculated by test-retest, spilt-half and Cronbach's alpha coefficient as 0.89, 0.75 and 0.82, respectively. The validity of the inventory was also investigated by convergent validity and exploratory factor analysis. The results from factor analysis and varimax rotation method yielded seven factors, including cooperativeness, harm- avoidance, novelty-seeking, reward-dependence, persistence, self- direction and self-transcendence which accounted for 59.19% of the total variance. The convergent validity was confirmed by computing a correlation coefficient between the subscales together and with total scale, which was significant between 0.62 and 0.71 (p<0.01). In conclusion, Cloninger’s preschool Temperament and Character Inventory generally proved to be a valid and reliable tool in evaluating the temperaments of the Iranian preschoolers.