Although young children display various types of interests, little is known regarding the potential impact of these interests on subsequent learning and development. Of particular importance is the question of whether or not children's early interests are instrumental in their later academic achievement. The current study fills this gap in the interest literature by longitudinally investigating the relationship between 116 children's early science interests and their subsequent self-concepts and science-related academic achievement, with particular emphasis placed on gender. The intensity and content of children's science interests between the ages of 4 and 6 (i.e., preschool interests) and between the ages of 6 and 8 (i.e., elementary school interests) were used as predictors of age 8 self-concept and science achievement. Boys displayed higher overall levels of science interests than girls, though interest was not related to boys' self-concepts. Girls' early intense science interests were related to higher science self-concepts at age 8. In addition, early interests predicted science achievement in girls but not in boys. In conclusion, it appears that early science interest may be a critical supporting factor for girls in fostering positive self-concepts and higher science achievement scores. (Contains 6 tables.)