We are experiencing a technology shift: Powerful and easy-to-use touchscreen-based mobile devices like smartphones and tablets are becoming more prevalent than traditional PCs and laptops. We propose that computer programming, and thus teaching of programming, can and should be done directly on the mobile devices themselves, without the need for a separate PC or laptop to write code. In this workshop, participants will learn about developing software directly on smartphones without a PC using TouchDevelop, a novel application creation environment on Windows Phone 7 from Microsoft Research (http://touchdevelop.com). Its typed, structured programming language is built around the idea of only using a touchscreen as the input device to author code. A semi-structured code editor makes it easy to navigate between different syntax elements. By inferring types and mining previously written programs, the editor provides highly predictive auto-completion suggestions to the user. The language provides built-in primitives that make it easy to access the rich sensor data available on a mobile device. Programming on mobile devices engages students in new ways, allowing them to access and manipulate programmatically their most personal digital data such as pictures, videos, and music. Programming on smartphones which we carry around with us at all times means instant gratification for students, as they can show their games and applications to their friends, and it means that students can do their homework or additional practicing at all times. For this workshop, a laptop is optional; Windows Phone 7 devices will be provided for exercises.