In recent years, malaria has emerged as a cause celebre for voguish philanthropists. Bill Gates, Bono, and Laura Bush are only a few of the personalities who have lent their names--and opened their pocketbooks--in hopes of stopping the disease. Still, in a time when every emergent disease inspires waves of panic, why aren't we doing more to tame one of our oldest foes? And how does a pathogen that we've known how to prevent for more than a century still infect 500 million people every year, killing nearly one million of them?