Disorders of puberty can profoundly impact physical and psychosocial well-being. Precocious puberty is pubertal onset before eight years of age in girls and before nine years of age in boys. Patients with early isolated pubertal changes, prepubertal linear growth, and no worrisome neurologic symptoms typically have a benign pattern of development and should be monitored in the appropriate clinical context. Among patients with true precocious puberty, or full activation of the hypothalamic-pituitary-gonadal axis, most girls have an idiopathic etiology, whereas it is commonly due to identifiable pathology on imaging in boys. History and physical examination should be followed by measurements of serum follicle-stimulating hormone, luteinizing hormone, and testosterone (boys) or estradiol (girls); thyroid function testing; and bone age radiography. Brain magnetic resonance imaging should be performed in girls younger than six years, all boys with precocious puberty, and children with neurologic symptoms. Delayed puberty is the absence of breast development in girls by 13 years of age and absence of testicular growth to at least 4 mL in volume or 2.5 cm in length in boys by 14 years of age. Constitutional delay of growth and puberty is a common cause of delayed puberty; however, functional or persistent hypogonadism should be excluded. History and physical examination should be followed by measurements of serum follicle-stimulating hormone, luteinizing hormone, and testosterone (boys) or estradiol (girls); and bone age radiography. Abnormal growth velocity necessitates assessment of serum thyroid function, prolactin, and insulinlike growth factor I. Boys 14 years and older and girls 13 years and older may benefit from sex steroid treatment to jump-start puberty. Referral to a pediatric endocrinologist may be warranted after the initial evaluation.