The Recreovia program provides free physical activity (PA) classes in public spaces in Bogota, Colombia. The purpose of this study was to assess the effectiveness of the Recreovia program in increasing PA among users of nine parks in Bogota. This study was a natural experiment conducted between 2013 and 2015 in Bogota. Community members and park users living nearby three groups of parks were compared: Group 1 were parks implementing new Recreovias (n = 3), Group 2 were control parks (n = 3) without Recreovias, and Group 3 were parks with existing Recreovías. Individuals in the “intervention” group were exposed to newly implemented Recreovia programs in parks near their homes. Measurements were collected at baseline and 6–8 months after the intervention started. A total of 1533 participants were enrolled in the study: 501 for the existing Recreovias (included in a cross-sectional assessment) and 1032 participants (from the new Recreovias and control parks) included in the cross-sectional and pre-post study. Most participants were low income females. Twenty-three percent of the intervention group started participating in the program. Users of existing Recreovias were significantly more active and less likely to be overweight/obese compared to new Recreovia users at baseline. No changes on PA were found when comparing the intervention and control groups. Recreovias may have potential for increasing PA at the population level in urban areas given their rapid scalability, the higher levels of PA observed among program users, and its potential to reach women, low-income, less educated populations, and the overweight and obese.