Psychology generally assumes that people are pretty much the same, but it neglects to take into account significant differences between people. There are two key 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 "a person's characteristic behavioral patterns that contribute to his or her uniqueness." In other words, personality is one of the psychological factors that differentiate each individual. There are three main approaches in sports psychology that are used to explain personality and how it can affect sports performance: the trait approach, the situational approach, and the interactional approach. Review each of these theories to try to determine whether or not personality affects athletic performance. APPROACH TO TRAITS Both Ysenck and Cattell developed theories based on the idea of ​​traits. These theories suggest that one'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 predictable ways” (Jenskins, 2005). Eysenck and Cattell suggest that traits are relatively stable and enduring characteristics and therefore allow us to predict a person's behavior. Eysenck (1950) suggests that personality is "the sum total of the organism's actual or potential behavioral patterns, as determined by heredity and environment." Eysenck developed a personality inventory (Eysenck and Eysenck, 1964) (in the middle of the article ......letes, non-lean sports athletes and nonathletes on behavioral and psychological indices of eating disorders. Journal of Applied Sport Psychology, 8(2), pp.218-230- Schurr, KT, Ashley, MA and Joy, KL, 1977. A multivariate analysis of male athlete characteristics: 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 April 19, 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 April 19, 2014]. RS and Gould, D., 1995. Foundations of Sport and Exercise Psychology Champaign, IL: Human Kinetics.