Clinicians often need to differentiate between benign, self-limited variations of pubertal development and more serious underlying causes. Precocious puberty should be considered when thelarche occurs in female patients before 8 years of age or when testicular enlargement occurs in male patients before 9 years of age. Delayed puberty should be considered in female patients who lack breast development by 13 years of age or do not experience menarche by age 15 and in male patients who lack testicular growth by age 14. Assessment should focus on clinical and family history, growth, and pubertal examination to rule out benign pubertal variations. Further laboratory and radiographic workup may include early morning testing of luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone (thyrotropin), total testosterone (in male patients), and estradiol (in female patients), as well as left-hand bone age radiography. Neuroimaging with contrast-enhanced magnetic resonance imaging of the brain should be obtained in all patients with central precocious puberty who have neurologic signs or symptoms; are female and younger than 6 years; or are male and younger than 9 years. Specialist evaluation by pediatric endocrinology is often indicated when examination results are not consistent with a benign variation of puberty.