Participation in organized sport is associated with enhanced psychological, social, and health outcomes, yet considerable dropout rates are observed in adolescence, particularly among girls. Affective factors are associated with sport experiences and may impact dropout in adolescent athletes, however, there is a dearth of longitudinal research examining sport dropout. The purpose of this longitudinal study was to identify affective factors (i.e., enjoyment, positive affect, negative affect, competitive anxiety) that may protect against or present risk for dropout from sport. Adolescent girls (Mage = 14.02 ± 1.38 years old) participating in organized sport were sampled at baseline (n = 518) and self-reported a range of affective indices, and were followed up 4 years later (n = 166) to track sport disengagement or dropout from sport altogether. At follow-up, 55% of respondents reported disengagement from at least one sport (81%), or completely withdrew from sport (19%). Controlling for age, the binary logistic regression model was significant, ?2(5) = 12.41, p < .05, and explained 11% (Nagelkerke R^2) of the variance in sport dropout. Girls with higher baseline competitive anxiety were 2.04 times more likely to dropout or sport over the next four years (p < 0.05). These findings suggest that competitive anxiety is an affective risk factor that may predict future sport disengagement. Developing strategies to target and reduce competitive anxiety among female athletes may contribute towards reduced sport disengagement, and allow girls to further realize the psychosocial and health benefits associated with sport participation.