A Knowledge Worker (KW) uses her computer to perform different tasks for which she gathers and uses information from disparate sources such as the Web and e-mail, and creates new information such as calendar events, e-mails, and documents (resources). This forms a Task Space (TS): an information space composed of all computer-based resources the KW uses in relation to a task. Furthermore, KWs may switch between multiple tasks, some of which may be suspended and resumed after some time. These effects compound the KW’s ability to organise and visualise an accurate mental model of the individual TSs. We propose a Task-Based User Model (TBUM) that acts as the KW’s mental model for each task by automatically tracking, relating and organising resources associated with that task. The generated TBUM can be used to support complex activities such as task-resumption, searching within a task-context, task sharing and collaboration. Key words: Task-Based Computing, Personal Knowledge Managem...