A sea change is underway among many of today’s girls: they are developing faster and entering puberty earlier than ever before. Just a generation ago, fewer than 5 percent of girls started puberty before the age of eight; today that percentage has more than doubled. Early puberty is not just a matter of physical transformation – it’s deeply psychological too, with effects that can put a girl at higher risk for behavioral problems as well as long-term health challenges such as obesity, depression, eating disorders, and even cancer. Why is this happening, and what does it mean for our girls’ futures? What can we do to help lead them through this major transition to live happy and healthy lives?