This study explores the relationship between academic achievement and reading motivation among adolescent boys. We seek to understand (1) if motivational construct scores change meaningfully over time, (2) what relationship exists between the achievement scores and reported reading motivation, and (3) if students who report higher reading motivation initially have greater gains in achievement over time than students who report lower reading motivation. Results suggest some variation in construct scores over time. Achievement scores obtained in eighth grade were predictive of numerous motivational construct scores in ninth grade; limited results suggest that motivation in ninth grade may affect later achievement.