Precocious puberty refers to the appearance of physical and hormonal signs of pubertal development at an earlier age than is considered normal. The onset of puberty before 7 or 8 years for white girls and 9 years for boys is considered precocious. Early onset of puberty can cause several problems. The early growth spurt initially can cause tall stature, but rapid bone maturation can cause linear growth to cease too early and can result in short adult stature. The early appearance of breasts or menses in girls and increased libido in boys can cause emotional distress for some children. Premature pubarche and premature thelarche are 2 common, benign, normal variant conditions that can resemble precocious puberty but are nonprogressive or very slowly progressive. A thorough history, physical examination, and growth curve review can help distinguish these normal variants from true sexual precocity. If the history, physical examination, and laboratory data suggest that a child exhibits early and sustained evidence of pubertal maturation, the clinician must differentiate central precocious puberty (CPP) from precocious pseudo puberty. Central precocious puberty, which is gonadotropin-dependent, is the early maturation of the entire hypothalamic-pituitary-gonadal (HPG) axis, with the full spectrum of physical and hormonal changes of puberty. Precocious pseudo puberty is much less common and refers to conditions in which increased production of sex steroids is gonadotropin-independent (Precocious pseudopuberty). Correct diagnosis of the etiology of sexual precocity is critical, because evaluation and diagnosis of patients with precocious pseudopuberty is quite different than that for patients with central precocious puberty.