Background: We evaluated the association between availability of specific physical activity (PA) spaces and PA practices among adolescents within Mexican high schools (HS). Methods: Data were collected through an online survey applied to principals or person in charge of 4023 Mexican HS during the 2015-2016 school year. Adequate PA was defined as moderate to vigorous intensity PA for =60 minutes/day, =5 days/week, whereas PA-specific spaces were considered those that were available and specifically designed/used for PA. HS demographic factors were explored as covariates. Associations were estimated using a logistic regression model. Results: From total participating HS, 83.10% had at least 1 PA-specific space and 31.07% had adequate PA practices. A higher number of PA-specific spaces was associated with greater adequate PA practices (33% to 61%). Possibilities for adequate PA increased when: physical education (PE) classes were led by a designated PE teacher (OR 2.39; 95%CI: 2.03-2.83); the number of enrolled students was higher (OR 1.78; 95%CI, 1.43-2.22 and OR 2.23; 95% CI, 1.71-2.89, second and third tertile, respectively); HS financing sources were autonomous or private (OR 1.76; 95% CI, 1.19-2.60); and HS were located in northern Mexico (OR 1.27; 95%CI, 1.02-1.57). Conclusion: PA-specific spaces, designated PE teachers, and financing sources are important factors in achieving adequate PA within Mexican high schools.