This paper describes a new digital user study tool called Mobile Probes. Mobile Probes arose from a need to develop contextual and dynamic self-documenting tools for studying people’s actions in mobile contexts. The technology used in the pilot study was based on dual band mobile phones with GPRS connections and an external accessory digital camera. A system was also developed for sharing and sorting the data. The system was implemented with Java software to enable the device to send and receive data, and PHP scripting to send and edit the questions and to view the answers through a dynamic web server. Another pilot study was conducted with a flexible platform that operates a spatio-temporal mobile log. The results of the studies show that Mobile Probes are a promising way to conduct user studies. Ideas for future development of the tool are discussed. Author Keywords User-centered concept design; User Studies; Mobile devices; Digital ethnography; Cultural Probes, Selfdocumenting; S...