Background. The high prevalence of childhood overweight and obesity is a health problem worldwide. In developing countries, we lack information on the extent of the problem and the risk factors involved. Objective. To determine the prevalence rates of overweight and obesity and of abdominal obesity, and their relationship with physical activity, poverty, and eating habits in schoolchildren in Cuenca, Ecuador. Methods. A cross-sectional survey in a representative sample (n = 743) schoolchildren aged 6 to 9 years was conducted. Overweight and obesity were detected using the International Obesity Task Force cutoffs according to body mass index (BMI), and abdominal obesity was detected according to waist circumference. Poverty, physical activity, and eating habits were assessed with validated questionnaires. Results. The prevalence rates of overweight and obesity and of abdominal obesity were 26.0% and 10.6%, respectively. There were no differences between the sexes, but the prevalence of overweight and obesity was 1.5- to 2-fold higher in 9-year-old than in 6-year-old children (p < .05). Multivariate models demonstrated that higher BMI and waist circumference were significantly related to low physical activity and nonpoverty. Insufficient physical activity (in 75% of children) was associated with a 13% to 18% increased risk of overweight and obesity and abdominal obesity. Eating breakfast and eating more than three meals per day (in 96.7% and 85.9% of children, respectively) were not related to the prevalence of overweight and obesity. Eating fruits during school break was associated with a lower BMI. Conclusions. The high prevalence of overweight and obesity observed in schoolchildren increased from the ages of 6 to 9 years and was associated with insufficient physical activity and nonpoverty. Promoting physical activity and fruit consumption in school snacks should be explored as intervention measures to prevent and reduce overweight and obesity in Cuenca schoolchildren.Cuencavol. 34; no. 4