Using two major data sets from the Texas Youth Fitness Study, ordinary least squares regression, and hierarchical linear modeling, we examined the impact of key correlates in school physical education programs and policies on students' fitness status and cross-grade differences. While a number of factors, such as teachers' training/updates, recess time, available physical activity space, a school wellness policy, and fitness testing before administration, were confirmed, these correlates can explain only limited variance. Other aspects, such as socioeconomic status and community confounding factors, were recognized and illustrated. Future studies should include more factors such as these in data collection and analysis. (Contains 8 tables.)