This study uncovers the predictive relationship of middle school students' ability beliefs (self-efficacy and expectancy-related beliefs) and incentives (outcome expectancy, importance, interest, and usefulness) to intention, cardiovascular fitness, and teacher-rated effort in physical education. Participants (N = 252; 118 boys, 134 girls) completed questionnaires assessing their ability beliefs, incentives, and intention for future participation in physical education, and then had their cardiovascular fitness assessed with the Progressive Aerobic Cardiovascular Endurance Run (PACER) test. Students' effort in class was rated by their respective physical education teachers. Correlation analysis yielded significantly positive relationships between ability beliefs and incentives. Regression results revealed that ability beliefs, importance, interest, and usefulness significantly predicted intention for future participation. Ability beliefs also emerged as significant predictors of PACER test scores whereas self-efficacy was the only predictor of teacher-rated effort. Implications for educational practice are discussed. (Contains 2 tables.)