Once considered an adult onset disease, type 2 diabetes is increasingly being diagnosed in low-income Mexican American children. Studies have suggested that most of those so diagnosed were overweight, reported low levels of physical activity, and were generally unaware of their disease. The Bienestar Health Program was designed to reduce risk factors associated with the onset of type 2 diabetes. A major focus of the curriculum is health and physical education. A comparison of intervention and control group students resulted in a significant difference in physical fitness change scores (p [is less than] .003) after an 8-month intervention. This study suggests that it is possible to improve the physical fitness of low-income Mexican American preadolescent children through a comprehensive school-based health program.