This study aimed to investigate the relationships between middle school students' expectancyrelated beliefs, task values (importance, interest, and usefulness), engagement and satisfaction in physical education class, and their cardiorespiratory fitness. The grade and gender differences of the motivational variables were also examined. Participants (N = 307; 101 sixth graders, 96 seventh graders, 110 eighth graders; 149 boys, 158 girls) completed questionnaires assessing their expectancy-related beliefs, perceptions of importance, interest, usefulness, and perceived engagement and satisfaction in physical education, then had their cardiorespiratory fitness assessed with the Progressive Aerobic Cardiovascular Endurance Run (PACER) test. Regression analyses yielded that importance, expectancy-related beliefs, and interest significantly correlated to perceived engagement, whereas interest, expectancy-related beliefs, and importance emerged as contributors of students' perceived satisfaction in physical education. Expectancy-related beliefs were the only significant contributor of students' PACER test. Significant differences emerged between sixth and eighth graders on importance, interest, and usefulness. In addition, boys scored significantly higher on expectancy-related beliefs and interest than girls did. These findings were discussed in regard to the implications for educational practice and areas for future research.