Cosmetic companies have started developing and selling products designed to harness the skin microbiome to help treat a range of skin conditions from acne to eczema. Skeptics, however, warn that touting such an approach is premature because scientists are still working to understand the bacteria that live on our skin and interact with it. The cover story in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society, scopes out the scene.