Mobile urban environments present a challenge for context-aware computers, because they differ from static indoor contexts such as offices, meeting rooms, and lecture halls in many important ways. Internal factors such as task goals are different-external factors such as social resources are dynamic and unpredictable. An empirical, user-centered approach is needed to understand mobile contexts. For these ends, we present insights from an ethnomethodologically inspired study. The data consist of travel episodes of 25 adult urbanites (incl. elderly, single mothers, adolescents) in Helsinki. We present how situational and planned acts intermesh in navigation, how people create personal spaces while waiting, and how temporal tensions develop and dissolve. Furthermore, we provide examples of social solutions to navigation problems, examine aspects of multitasking, and consider design implications for context-aware mobile computing.