Precocious puberty is puberty occurring earlier than 2.5 SD below the mean. In boys, this is before age 9. In girls, the age is controversial, but classically, has been considered age 8 for white girls and 7 for African American girls. Precocious Puberty can be centrally or peripherally mediated and is more common in girls than boys. In central precocious puberty (CPP) the concern is to identify whether the etiology is pathological or idiopathic. In girls, the cause of CPP is usually idiopathic but in boys a central lesion is more common. The most commonly identified cause of CPP is the hypothalamic hamartoma. A head MRI should be considered in any child with CPP to rule out occult intracranial lesions.