[Abstract] Researchers interested in individual differences have long sought to categorize personality and to develop a succinct model in order to achieve consistency within different academic fields. As a result of this, the Big Five-Model of Personality has emerged as the dominant model, describing personality in terms of five different traits. Various questionnaires have been developed to measure these traits and the International Personality Item Pool（IPIP）is a well-established and relatively concise example. The current study attempted to determine the reliability and dimensionality of the extraversion dimension of the IPIP by use of Rasch analysis to examine the results of ７９ university students who completed the extraversion part of the IPIP measure. Results showed that generally the questions fit the Rasch model and support the unidmensionality of the extraversion dimension of the IPIP test.