This research project aims to develop a data collection application that enables real-time tracking and reporting of the health-related impacts of travel behavior. Using computing, communication, and sensing capabilities of smartphones, an Android phone application?named UbiActive?was developed to collect real-time travel-related physical activity and psychological well-being data from phone users. The application was tested on multiple Android phones, among which Nexus S and HTC Magic were found to produce comparable physical activity outputs with the commercially available accelerometer. The application was further tested in a three-week field study for its viability for real-time data collection and behavior intervention against unhealthy travel behavior. Twenty-three young adults were recruited and randomized into intervention and control groups. Both groups were asked to install UbiActive on their phone and wear their phone on their right hip during all waking hours for three consecutive weeks. The intervention group was provided information on impacts of their travel behavior on physical activity and psychological well-being. No information was provided to the control group. After the field study, all participants were asked to complete a web-based exit survey that was comprised of questions about their general participation experience and specific concerns about the study design, application, compliance requirements, and privacy issues. Findings from the field study show that UbiActive has high potential in collecting travel-related physical activity and psychological experience data, but limited effectiveness in behavior intervention. Findings from the exit survey provide useful insights into potential improvement areas of the study and the UbiActive application.