We present a novel approach for extending the input spacearound unmodified mobile devices. Using built-in front-facing cameras of unmodified handheld devices, GlassHandsestimates hand poses and gestures through reflections in sun-glasses, ski goggles or visors. Thereby, GlassHands createsan enlarged input space, rivaling input reach on large touchdisplays. We introduce the idea along with its technical con-cept and implementation. We demonstrate the feasibility andpotential of our proposed approach in several applicationscenarios, such as map browsing or drawing using a set ofinteraction techniques previously possible only with modifiedmobile devices or on large touch displays. Our research isbacked up with a user study.