Childhood obesity has increased in both developed and developing countries although the pace and pattern differ from country to country. It has profound public health consequences, as seventy percent of the overweight children become overweight adults. The present study was focused on the prevalence of childhood obesity in selected schools of Kottayam district and to explore the association of obesity with variables like socio economic status, location of residence, birth weight of the child, nutrition during infancy and life style pattern. A total of 2216 children were selected from eight public schools which constitute 1008 boys and 1208 girls in the age group of 10 to 14 years. A well framed questionnaire was distributed to elicit details on demographic profile, life style and food consumption pattern. Height and weight was taken for all the children to identify the BMI and status of body fat. Of the total population 18 percent were obese, 14 percent were overweight, 56 percent were normal weight and 12 percent were underweight. The results of the study exposed the fact that the percentage of overweight and obese children are growing in Kerala also, like in the other states of India and globally. Obesity and overweight were seen more in girls and underweight seemed to be more in boys indicating an increasing trend in the percentage of obesity among girls compared to boys. In rural areas also an increasing trend of overweight and obesity was observed although underweight children are still prominent. So it was concluded that the increasing trend of the modern day epidemic of overweight and obesity in children calls for immediate action to reduce the incidence through appropriate nutrition intervention programmes involving school children, their parents and school authorities. If immediate measures are not taken the condition can lead to serious problems beyond repair.