Forty-three children participated in a longitudinal study of mastery motivation. Children's levels of mastery motivation (persistence) and cognitive functioning were measured at ages 2 and 8. In addition, academic achievement was measured at age 8. Task persistence was stable across time for girls only, but maternal reports of mastery motivation were not consistent across the two ages for either gender. Maternal reports, but not task persistence, at age 2 predicted cognitive functioning and academic achievement at age 8 for girls. No predictive relationships were evident for boys, and boys were significantly less persistent than girls with a task requiring sustained effort at age 8. The findings offer empirical support for the view that early motivation is important for later functioning. Significant gender differences suggest that, in this respect, girls and boys may develop differently or be influenced by different contextual experiences. The need for educators to base their practice on a more complete understanding of how motivation develops in both boys and girls is stressed.