Developing breasts is usually the first sign of puberty

Developing breasts is usually the first sign of puberty. For most girls this will be around the age of 10 or 11 but could be up to the age of 15. Puberty is different for each girl, so don't worry if your best friend develops breasts before you, yours will begin to develop when your body is ready. You may notice that your breasts might feel painful or tender as they start to develop which is down to the hormones released during puberty.