Since 1910, when Freud attributed Leonardo da Vinci's brilliance in part to his repressed sexuality, biographers have tried to decipher the psyches of the gifted and famous. Did Elvis have a Christ complex? Was Winston Churchill bipolar?

"Trying to understand someone by giving them a diagnosis is virtually worthless," says psychologist William Todd Schultz, who argues that a word simply names a behavior without adding new meaning to it. As editor of the forthcoming Handbook of Psychobiography (Oxford University Press) and professor at Pacific University in Oregon, Schultz takes an academic approach to the analysis of historical figures' inner lives. His book, the first introductory text on the practice of psychobiography, explains how to use psychological theory and research to shed new light on the achievements of complex people, instead of just giving them a label.

Most popular biographies today incorporate aspects of psychobiography, says Schultz, "but since most biographers don't really know psychology, they do kind of a crappy job." Schultz points to a book that reduced Bill Clinton to an "adult child of an alcoholic" and another that diagnosed John Lennon as having multiple personalities.

But popular biographies can succeed at psychological analysis, especially when writers carefully explore the subtleties of a subject's personality. Ray Monk brought philosopher Ludwig Wittgenstein to life, according to Schultz, and Janet Malcolm wrote a rich and revealing portrait of poet Sylvia Plath.