Concerns about problems of the breast are often noted in adolescents and their parents. This review discusses issues and disorders of the breast in children and adolescents, starting with basic principles of embryology and adolescent breast development. Concepts that are covered include congenital breast disorders, abnormal timing of breast development, breast asymmetry, underdeveloped breasts, breast atrophy, tuberous breasts, mammary hyperplasia, fibroadenoma, giant fibroadenoma, cystosarcoma phyllodes, intra-ductal breast papilloma, adenocarcinoma, mastitis, traumatic breast disorders, benign breast disease, fibrocystic change, mastalgia, gynecomastia, and galactorrhea. A number of figures are provided illustrating breast pathologic findings. Clinicians caring for children and adolescents are encouraged to provide careful assessments of this important organ.