Purpose: This study examines the effects of the middle school SPARK physical education (PE) curriculum on predisposing, enabling, and reinforcing factors for physical activity (PA) as well as self-reported PA in a predominantly low-income, Latinx student population in Los Angeles, CA. Methods: Data were collected from 3763 students of seventh and eighth grades at 2 time points at the 16 middle schools enrolled in the study. Hierarchical logistic regression models were used to assess intervention effects on PA attitudes, PE enjoyment, FitnessGram passing, daily PA, and muscle-strengthening PA, controlling for demographic variables. Results: Although there was no detectable intervention effect on increasing the number of students exercising 60 minutes per day, there was a negative intervention effect detected for muscle-strengthening exercises. A significant positive intervention effect was detected for both PE enjoyment and FitnessGram passing. Deeper analysis of these findings revealed that the positive effect on PE enjoyment occurred only among male students. Conclusion: The SPARK curriculum had mixed effects on students’ PA behavior as well as predisposing, enabling, and reinforcing factors for PA. Incorporating student perspectives into the evaluation of intervention efforts to promote PA can facilitate a better understanding of the ways in which these efforts influence PA behaviors and its determinants.