In order to develop a successful mobile application, it is necessary that the experience fits into people’s lives and solves real problems that they face. In Motorola Labs, we often finish exploratory ethnographic work with hundreds of design ideas for new mobile experiences. In order to identify those with the most value, we prototype key components of these ideas and test them with real people in their daily lives. I’ll talk about our strategies for rapid prototyping and field evaluation using examples from our work on the Ambient Mobile Communications program.