Leonard Sax is an American psychologist and family physician. He is the author of Why Gender Matters (Doubleday, 2005; revised edition to be published in 2017); Boys Adrift: the five factors driving the growing epidemic of unmotivated boys and underachieving young men (Basic Books, 2007; revised edition, 2016); Girls on the Edge (Basic Books, 2010); and The Collapse of Parenting (Basic Books, 2015). The Collapse of Parenting became a New York Times bestseller.