Pervasive and ubiquitous computing has the potential to make huge changes in the ways that we will learn throughout our lives. This paper presents a vision for the lifelong user model as a first class citizen, existing independently of any single application and controlled by the learner. The paper argues that this has a key role for a vision of personalized lifelong learning and for augmented cognition that enables learners to supplement their own knowledge with readily accessible digital information based on documents that they have accessed or used. The paper presents work that provides foundations for this vision. First, it outlines technical issues and research into approaches for addressing them. Then, it presents work on the interface between the learner and the lifelong user model, an aspect that is important because the human issues of control and privacy are so central. The final discussion and conclusions outline a roadmap for future research that will underpin this vision o...