The entry into the adolescent years is heralded by physical development that occurs in response to hormonal changes. For girls, breast enlargement, growth of pubic hair, and the onset and regularization of menstruation are prominent features. For boys, growth of testicles, the penis, and pubic hair are visible changes, while voice changes are publicly evident. For girls and boys, acne and body odor changes are common. Clinicians can guide adolescents through these changes. Early (prior to eight years of age in girls and nine years of age in boys) onset of pubertal changes should prompt evaluation and potential management for either central or peripheral pathologies. Similarly, delayed puberty (lack of secondary sexual characteristics by age 13 in girls and 14 in boys, lack of menstruation by age 15 in girls) can be due to centrally-mediated disorders, including systemic diseases, and to end-organ defects. Specific treatments are available for early and delayed puberty, menstrual disorders (limited or heavy or painful bleeding, mood changes), and polycystic ovary syndrome. Hormonal supplementation and regulation can often be very helpful.