Objectives. To examine the impact of physical education (PE) litigation on changes in cardio-respiratory fitness among racially/ethnically and socioeconomically diverse students.Methods. We used annual school-level data for all California schools with measures of fifth graders' cardio-respiratory fitness spanning 2007-2008 through 2017-2018. A difference-in-difference design assessed changes before and after lawsuits in the proportion of students meeting fitness standards in schools in districts that were parties to PE lawsuits (n = 2715) versus in schools in districts not involved (n = 3152). We ran separate models with the proportion of students meeting fitness standards by sex, race/ethnicity, and low-income status as outcomes.Results. PE litigation led to a 1-percentage-point increase in the proportion of fifth-grade students meeting cardio-respiratory fitness standards (95% confidence interval [CI] = 0.03%, 2.0%). Effects were especially pronounced for female (1.3-percentage-point increase; 95% CI = 0.1%, 2.5%), African American (3.4-percentage-point increase; 95% CI = 0.5%, 6.2%), and low-income (2.8-percentage-point increase; 95% CI = 0.5%, 6.0%) students.Conclusions. Schools in districts subject to PE litigation showed greater improvements in student fitness, particularly among students typically at higher risk for inactivity and low fitness. Litigation may be an impactful tool for enforcing PE provision in accordance with the law.