Despite what the overcrowded, overpriced shelves of your pharmacy might suggest, pharmaceutical companies struggle to find new drugs these days. The low-hanging fruit is long gone, and the main discovery method that served so well in past decades is generating far fewer hits today. But a fresh strategy, focused on a property called allosterism, is now invigorating many investigators. Some predict it will revolutionize drug discovery and could deliver treatments for diseases that so far remain intractable.