Short stature is defined as a height more than two standard deviations below the mean for age (less than the 3rd percentile). Tall stature is defined as a height more than two standard deviations above the mean for age (greater than the 97th percentile). The initial evaluation of short and tall stature should include a history and physical examination, accurate serial measurements, and determination of growth velocity, midparental height, and bone age. Common normal variants of short stature are familial short stature, constitutional delay of growth and puberty, and idiopathic short stature. Pathologic causes of short stature include chronic diseases; growth hormone deficiency; and genetic disorders, such as Turner syndrome. Tall stature has the same prevalence as short stature, but it is a much less common reason for referral to subspecialty care. Common causes of tall stature include familial tall stature, obesity, Klinefelter syndrome, Marfan syndrome, and precocious puberty. Although most children with short or tall stature have variants of normal growth, children who are more than three standard deviations from the mean for age are more likely to have underlying pathology. Evaluation for pathologic etiologies is guided by history and physical examination findings.