Recently in the apparel industry, early adolescent girls are emerging as a new consumer group. In response to this, companies are developing clothes, cosmetics, underwear, etc. This study proposed a new size range and size interval for early adolescent girls and presented reference measurements for body parts necessary in designing clothes. For this purpose, a total of 529 girls aged between 10 and 14 were measured and data were collected from 42 anthropometric measurements and 41 photographic measurements per a person. SAS 8.1 was used in data analysis including means, standard deviations, frequency analysis. Based on the results, this study proposed: for Type A - 7 sizes (140A-67, 145A-65, 145A-69, 150A-69, 150A-73, 155A-73, 155A-76): for Type X - 7 sizes (150x-72, 155x-72, 155x-77, 160x-77, 160x-80, 165x-77, 165x-80); and for Type H - 8 sizes (145H-74, 145H-82, 150H-78, 150H-82, 155H-82, 155H-86, 160H-86, 160H-88). Reference measurements suggested for upper garments were 9 items. The outcome of this study may be used as a basic material for adolescent apparel manufacturers to set their apparel sizing system and to supply their consumers, namely, adolescent girls with products fitting their somatotype.