Reading activities in the classroom and workplace occur predominantly on paper. Since existing electronic devices do not support these reading activities as well as paper, users have difficulty taking full advantage of the affordances of electronic documents. This dissertation makes three main contributions toward supporting active reading electronically. The first contribution is a comprehensive set of active reading requirements, drawn from three decades of research into reading processes. These requirements explain why existing devices are inadequate for supporting active reading activities. The second contribution is a multi-slate reading system that more completely supports the active reading requirements above. Researchers believe the suitability of paper for active reading is largely due to the fact it distributes content across different sheets of paper, which are capable of displaying information as well as capturing input. The multi-slate approach draws inspiration from the independent reading and writing surfaces that paper provides, to blend the beneficial features of e-book readers, tablets, PCs, and tabletop computers. The development of the multi-slate system began with the Dual-Display E-book, which used two screens to provide richer navigation capabilities than a single-screen device. Following the success of the Dual-Display E-book, the United Slates, a general-purpose reading system consisting of an extensible number of slates, was created. The United Slates consisted of custom slate hardware, specialized interactions that enabled the slates to be used cooperatively, and a cloud-based infrastructure that robustly integrated the slates with users' existing computing devices and workflow. The third contribution is a series of evaluations that characterized reading with multiple slates. A laboratory study with 12 participants compared the relative merits of paper and electronic reading surfaces. One month long in-situ deployments of the United Slates with graduate students in the humanities found the multi-slate configuration to be highly effective for reading. The United Slates system delivered desirable paper-like qualities that included enhanced reading engagement, ease of navigation, and peace-of-mind while also providing superior electronic functionality. The positive feedback suggests that the multi-slate configuration is a desirable method for supporting active reading activities. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]