This chapter discusses some of the primary issues related to the design and construction of natural language interfaces, and in particular, interfaces to mobile devices. It describes two systems in this space: the START information access system and the StartMobile natural language interface to mobile devices. The chapter also discusses recently deployed commercial systems and future directions. The use of natural language annotations, and in particular, parameterized natural language annotations, enables START to respond to user requests in a wide variety of ways. StartMobile uses the START system as a first stage in the processing of user requests. Current commercial systems such as Apple's Siri, IBM's Watson, Google's “Google Now”, Microsoft's Cortana, and Amazon's Alexa employ technology of the sort contained in START and StartMobile in combination with statistical ...