ObjectiveTo identify whether sex disparities in leisure-time physical activity (LTPA) vary across population subgroups. Participants and MethodsWe used data from the Behavioral Risk Factor Surveillance System (BRFSS) spanning 2011 to 2021. We examined subgroups by age, race/ethnicity, income, employment, education, marital status, body mass index, and cardiometabolic comorbidities (diabetes, hypertension, and cardiovascular disease) to identify where sex disparities in LTPA are most pronounced. ResultsAmong 4,415,992 respondents (57.4% [2,533,234] women and 42.6% [1,882,758] men), women were less likely than men to report LTPA (73.0% vs 76.8%; odds ratio [OR], 0.817; 95% CI, 0.809 to 0.825). The gap was widest between the youngest (OR for the 18- to 24-year age group, 0.71; 95% CI, 0.68 to 0.74) and oldest (OR for the 80 years or older age group, 0.71; 95% CI, 0.69 to 0.73) respondents but was narrower between middle-aged adults (OR for the 50- to 59-year age group, 0.95; 95% CI, 0.93 to 0.97). Disparity was greater among non-Hispanic Black participants (OR, 0.70; 95% CI, 0.68 to 0.72) and Hispanic participants (OR, 0.79; 95% CI, 0.77 to 0.81) than among non-Hispanic White participants (OR, 0.85; 95% CI, 0.84 to 0.86). Disparities were greater at the lowest income levels (OR, 0.81; 95% CI, 0.78 to 0.85) and lower at the highest income levels (OR, 0.94; 95% CI, 0.91 to 0.96). The disparity was greater in unemployed individuals (OR, 0.78; 95% CI, 0.76 to 0.80) compared with employed individuals (OR, 0.91; 95% CI, 0.90 to 0.92). Moreover, disparity was greater in individuals with a body mass index in the overweight or obese range and those with diabetes, hypertension, or cardiovascular disease. ConclusionWomen are less likely than men to engage in LTPA. These disparities are greatest among the young and elderly, Black and Hispanic individuals, lower income and unemployed individuals, and individuals with cardiometabolic disease. Targeted interventions are needed to reduce sex-related disparities.