This document discusses mobile phones as mediating tools for learning within augmented contexts. It argues that the design of mobile learning experiences needs to be re-examined to take advantage of mobile devices' affordances. Design research is presented as an approach that is iterative, interventionist, and contributes to theory building. An example of augmented contexts for development places context as a core construct for collaborative, location-based, problem solving using mobile devices. The paper concludes by outlining how design principles and implications for theory will be developed.