What do these people have in common?• The traveling businessman who brings prostitutes back to his hotel room • The wealthy woman who is arrested for shoplifting• The seemingly happily married man who cruises gay clubsThey are all—despite differences in degree, gender, and age—living a double life, one of our most deeply ingrained, but poorly understood psychological drives. Now, Dr. Gail Saltz steps into the breach to explore —in detail and based on the latest research—our impulse to create and nurture alter egos.Saltz reveals how assuming a different identity can be healthy and tremendously liberating. For proof, we need look no further than the innumerable people who reinvent themselves by moving to the big city, or the countless pseudonymous bloggers.