Physical activity is an important component of strategies for health promotion and prevention of noncommunicable diseases. It is also associated with decreased risk for cardiovascular disease in overweight and obese adults and children. This article addresses the initial description of a physical activity intervention for children attending public elementary schools in Mexico. The objective was to develop a replicable model based on a strategic public, private, academic, and social partnership that would have a short-term impact on the metabolic health of children and be useful for building effective public policy. Forty-nine schools (20 000 students) participated, and 5 schools were selected for evaluation. The intervention included a 30-minute supervised middle-effort interchangeable routine, 5 days a week for a complete school year, adapted for different school conditions and students of different ages. Evaluation included anthropometric measurements and biochemical markers. Actual prevalence of combined overweight and obesity in these children was 31.9%. The intervention was successfully implemented in all schools. No change in body mass index, waist circumference, or other anthropometric indicators was found. However, changes in biochemical markers showed a significant decrease in blood glucose, total cholesterol, and cholesterol-low-density lipoproteins, reflecting a positive effect on cardiovascular health indicators. © The Author(s) 2016. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.