Psychology usually assumes that people are more or less the same, but this neglects to consider the significant differences between people. There are two key subject areas in the study of human individual differences: personality and mental abilities; including the concept of intelligence. Psychometric measurement allows us to examine both common characteristics and differences between people. Research on sports personality has existed since the 1800s. Jenkins (2005) defines personality as “characteristic behavior patterns of a person that contribute to his or her uniqueness.” In other words, personality is one of the psychological factors that make every individual different. There are three main approaches in sports psychology that are used to explain personality and how it can influence sports performance: trait approach, situational approach and interactional approach. review each of these theories, to try to understand whether personality influences sports performance or not. TRAIT APPROACH Both Ysenck and Cattell developed theories based on the idea of ​​traits. These theories suggest that anyone's personality is made up of characteristics/traits that primarily define how the individual will behave in a situation. Traits are defined as “a person's predisposition to behave in a predictable manner” (Jenskins, 2005). Eysenck and Cattell suggest that traits are relatively stable, long-lasting characteristics and therefore allow us to predict someone's behavior. Eysenck (1950) suggests that personality is “the sum total of the organism's actual or potential behavior patterns, as determined by heredity and environment.” Eysenck developed a Personality Inventory (Eysenck and Eysenck, 1964) (if...... half of the article ...... athletes, non-lean athletes and non-athletes on the behavioral and psychological indices of eating disorders. Journal of Applied Sport Psychology, 8(2), pp.218-230- Schurr, K.T., Ashley, M.A. and Joy, K.L., 1977. A multivariate analysis of the characteristics of male athletes: sport type and success Multivariate experimental clinical research, 3 , pp. 53-68. - Sword, L., 2002. The Gifted Introvert. Available at: http://talentdevelop.com/articles/GiftIntrov.html [Accessed 19 April 2014]. - Talyabee, SR, Moghadam, RS and Salimi, M., 2013. The investigation of personality characteristics in student athletes and non-athletes. European Journal of Experimental Biology, [online]Available at [Accessed 19 April 2014].- Weinberg, RS and Gould,D. , 1995. Fundamentals. Sports and Exercise Psychology