Allan Wigfield examines the expectancy-value model of achievement motivation developed by Eccles et al. (1983) from a developmental perspective. The model posits that individuals' expectancies for success and the value they place on success are key determinants of their motivation to perform different achievement tasks. Wigfield discusses recent research on the development of young children's competence beliefs, expectancies for success, subjective task values, and achievement goals. He explores changes in these constructs over time, including shifts in the factor structure, mean levels, and conceptions of ability beliefs and subjective values. Additionally, he examines how achievement goals are conceptualized in the model and how they are understood by other current motivation researchers. The article also considers changes in the relationships among competence beliefs, subjective task values, achievement goals, and achievement behaviors.Allan Wigfield examines the expectancy-value model of achievement motivation developed by Eccles et al. (1983) from a developmental perspective. The model posits that individuals' expectancies for success and the value they place on success are key determinants of their motivation to perform different achievement tasks. Wigfield discusses recent research on the development of young children's competence beliefs, expectancies for success, subjective task values, and achievement goals. He explores changes in these constructs over time, including shifts in the factor structure, mean levels, and conceptions of ability beliefs and subjective values. Additionally, he examines how achievement goals are conceptualized in the model and how they are understood by other current motivation researchers. The article also considers changes in the relationships among competence beliefs, subjective task values, achievement goals, and achievement behaviors.