Sport has been identified as a context in which youth encounter positive and negative experiences. However, relatively little is known about the factors that lead to positive and negative personal development among sport participants. The purpose of this study was to investigate the role of enjoyment and motivational climate on positive and negative personal development of team sport participants. A sample of 510 athletes between the ages of 9 and 19 completed questionnaires on positive and negative personal development, enjoyment, and motivational climate. Stepwise multiple regression analyses examined the effects of enjoyment and motivational climate on the personal development of the athletes. Results demonstrated that positive experiences in sport were most strongly predicted by affiliation with peers, self-referenced competency, effort expenditure, and a task climate. Negative experiences were most strongly predicted by an ego climate and other-referenced competency. Results suggest that creating an environment that encourages peer affiliation and personal achievement can result in the positive personal development of youth sport participants.Sport has been identified as the most popular structured activity for youth participation (Mahoney, Larson, Eccles, & Lord, 2005). Recently, Guèvremont, Findlay, and Kohen (2008) reported that approximately 76% of Canadian youth between the ages of 6 and 17 years participated in at least one structured sport activity in the past year. In the United States, it is estimated that approximately 62% of high school students participated on at least one school or nonschool sport team in the Personal Development Through Sport 33 previous year (Pate, Trost, Levin, & Dowda, 2000). These data demonstrate that the majority of North American youth have some experience with organized sport. Weiss and Williams (2004) summarized the reasons why youth participate in sport. They suggested that youth participate for reasons of physical competence/ adequacy (i.e., improve skills, achieve goals), social acceptance (i.e., make new friends, team atmosphere), and enjoyment (i.e., energy release, excitement). These reasons point to the complexity of youth sport involvement, and demonstrate that individual (i.e., enjoyment) and environmental (i.e., team atmosphere) factors are important for understanding participation. Weiss and Williams concluded that participation in youth sport can be enhanced by (a) making sure the sport is enjoyable, (b) creating a task-oriented motivational climate, (c) providing social support, and (d) helping children help themselves. These recommendations highlight enjoyment and motivational climate as critical factors for prolonged participation of youth in sport. The following paragraphs elaborate on the relationship between enjoyment, motivational climate and youth sport.Enjoyment is consistently associated with continued sport participation (Scanlan, Carpenter, Schmidt, Simons, & Keeler, 1993;Scanlan, Stein, & Ravizza, 1989;Weiss, Kimmel, & Smith, 2001;Wiersma, 200...