The present study advances understanding of (a) the development of achievement goals, (b) the changing association of achievement goals and achievement over time, and (c) the implications of changes in achievement goals for changes in achievement over time. African American and European American adolescents' (N = 588) achievement goals and subsequent achievement were assessed at 4 time points (fall and spring of 6th and 7th grades) and modeled using growth-curve analytic techniques. There was an overall decline in all 3 types of achievement goals (mastery, performance-approach, and performance-avoidance goals), because of within-year rather than between-year decreases. The association between mastery goals and achievement was null at Time 1 and then positive at the following 3 time points. The association between performance-approach goals and achievement went from negative to null across time. Changes in students' goals, as well as their initial levels of goals, were particularly important in understanding how mastery goals foreshadow achievement. The implications of the findings for both theory and practice are discussed. (Contains 9 footnotes, 7 tables, and 3 figures.)