Electronic documents form an integral part of the modern computer age---virtually all personal computers have the ability to create, store and display their content. A connection to the Internet provides users with an almost endless source of documents, be they web-pages, word-processor files or emails. However, the entire contents of an electronic document are often too large to be usefully presented on a user’s screen, at a single point in time. This issue is usually overcome by placing the content inside a scrolling environment. The view onto the document is then modified by directly adjusting a scrollbar or by employing tools such as the mousewheel or paging keys. Applications may also provide methods for adjusting the document’s zoom and page layout. The scrollbar has seen widespread adoption, becoming the default tool used to visualise large information spaces. Despite its extensive deployment, researchers have little knowledge on how this and related navigation tools are used in an everyday work environment. A characterisation of users’ actions would allow designers to identify common behaviours and areas of inefficiency as they strive to improve navigation techniques. To fill this knowledge gap, this thesis aims to understand and improve navigation within desktop-based electronic documents. This goal is achieved using a five step process. First, the literature is used to explore document navigation tasks and the tools currently available to support electronic document navigation. Second, a software tool called AppMonitor, that logs users’ navigation actions, was developed. Third, AppMonitor was deployed in a longitudinal study to characterise document navigation actions in Microsoft Word and Adobe Reader. Forth, to compliment this study, two task-centric observations of electronic document navigation were performed, to probe the reasons for navigation tool selection. Finally, the Footprints Scrollbar was developed to improve one common aspect of navigation—within-document revisitation. To begin, two areas of current knowledge in this domain are overviewed: paper and electronic document navigation and electronic document navigation tools. The literature review produced five categories of document navigation tasks: ‘overviewing and browsing’, ‘reading’, ‘annotating and writing’, ‘searching’ and ‘revisitation’. In a similar fashion, electronic document navigation tools were reviewed and divided into eight categories: core navigation tools (those commonly found in today’s navigation systems), input devices, scrollbar augmentations, content-aware navigation aids, visualisations that provide multiple document views, indirect manipulation techniques, zooming tools and revisitation tools. The literature lacked evidence of an understanding of how these current document navigation tools are used. To aid the gathering of empirical data on tool use, the AppMonitor tool was developed. It records user actions in unmodified Windows applications—specifically for this research, Microsoft Word and Adobe Reader. It logs low-level interactions such as “left mouse button pressed” and “Ctrl-f pressed” as well as high level ‘logical’ actions such as menu selections and scrollbar manipulations. It requires no user input to perform these tasks, allowing study participants to continue with their everyday work. To collect data to form a characterisation of document navigation actions, 14 participants installed AppMonitor on their computer for 120 days. This study found that users primarily employ the mousewheel, scrollbar thumb and paging keys for navigation. Further, many advanced navigation tools that are lauded for their efficiency, including bookmarks and search tools, are rarely used. The longitudinal study provided valuable insights into the use of navigation tools. To understand the reasons behind this tool use, two task-centric observations of electronic document navigation were conducted. The first asked participants to perform a series of specific navigation tasks while AppMonitor logged their actions. The second was performed as a series of interactive sessions, where users performed a particular task and were then probed on their tool choice. These two studies found that many users are not aware of the advanced navigation tools that could significantly improve their navigation efficiency. Finally, the characterisations highlighted within-document revisitation as a commonly performed task, with current tools that support this action rarely used. To address this problem, the analysis, design and evaluation of a Footprints Scrollbar is presented. It places marks inside the scrollbar trough and provides shortcuts to aid users return to previously visited locations. The Footprints Scrollbar was significantly faster and subjectively preferred over a standard scrollbar for revisitation tasks. To summarise, this thesis contributes a literature review of document navigation and electronic document navigation tools; the design and implementation of AppMonitor—a tool to monitor user actions in unmodified Windows applications; a longitudinal study describing the navigation actions users perform; two taskcentric studies examining why actions are performed; and the Footprints Scrollbar, a tool to aid within-document revisitation tasks.