Boys begin puberty sometime between the ages of 9 and 14, with most boys starting between the ages of 11 and 13. However, it can also be normal to start earlier or later. Black and Hispanic boys tend to enter puberty a bit earlier than white boys. If a boy starts showing signs of puberty before age 9, or if no signs of puberty have happened by age 15, it’s worth asking his pediatrician about these early changes or delay. The earliest sign of puberty in boys is enlargement of the testicles, followed by growth of the penis and pubic hair. Puberty happens when the pituitary gland starts making more of two hormones, luteinizing hormone (called LH) and follicle-stimulating hormone (called FSH), which cause the testicles to grow and produce the male hormone testosterone. Boys finish their growth and physical development in Stage 5 of puberty, which usually occurs between the ages of 14 and 17, but some may continue growing through their early 20s.