Objective. The aim of this study was to develop a gender-appropriate pictorial scale to measure body image in young children based on a measurable index of adiposity. Method. Pictorial scales for boys and girls containing seven body pictures representing standard percentile curves for body mass index (BMI) for healthy children were developed. The Children's Body Image Scale (CBIS) was administered to 312 children aged between 7 and 12 years. Results. Accuracy of body size perception, indicated by the correlation between actual and perceived BMI category figure, developed with age, girls acquiring accuracy earlier than boys. Whereas girls developed a good accuracy (r = .60, p < .001, 10-12 years), in boys, the correlation, though significant, was not strong (r = .35, p < .01, 10-12 years). There was a consistent bias towards underestimation of body size using this technique. There was a high frequency of body size dissatisfaction across all the age ranges, 48% girls and 36% boys wished to have a smaller body figure than their own, and only 10% of girls and 20% boys wished to have a larger body figure. Construct validity was assessed in a subset of 153 children in which additional measures of restrained eating (DEBQ-R) and body esteem were available. From the age of 8 years, the CBIS provides a good measure of body dissatisfaction. Conclusions. The CBIS provides a good measure of body size perception in girls and an adequate measure in boys aged 8 years and older. It also provides a good measure of body size dissatisfaction in children. Internalization of a thin body ideal takes place at a young age, many children desiring a BMI below the average norm.