Officially, Prozac has been approved only for treating two serious mental diseases: clinical depression and obsessive-compulsive disorder. But millions of people in the U.S. are turning to the distinctive green-and-white capsules just to pull themselves out of the dumps. They've helped make Prozac one of the world's most widely prescribed medications. Prozac's extensive use has sparked an intense debate over the use of psychoactive drugs vs. talk therapy to treat mental illness, and raised questions about whether such drugs are tempting essentially healthy people to use “cosmetic psychopharmacology” to fine-tune their personalities. Even as the debate rages, there is agreement that the controversy has focused much-needed attention on depression -- the most common, and most treatable, serious mental illness.