Could people use tagging to manage day-to-day work in their personal computing environment? Could tagging be sufficiently generic and lightweight to support diverse ways of working and, perhaps, support new and efficient practices for managing applications and accessing documents? We investigate these issues by implementing the TAGtivity system that enables users to tag resources in the context of their ongoing work. We deployed TAGtivity and studied users’ tagging practices in their actual work places over a three week period. Our analysis of interviews and logs reveals that affordances of the TAGtivity system supported users in a variety of information and activity management tasks. These include new practices for managing emerging activities and ephemeral information and accessing documents across application data silos.