The ChemPaths Student Portal is more than just an online textbook, it incorporates linked problems, multimedia, and interactive 3-D structures. ChemPaths also incorporates navigation that takes advantage of research in hypertext learning. In addition to describing the development and use of ChemPaths in courses, this chapter describes the theoretical basis for its design. These stem from research in chemical education, hypertext learning, and applied constructivist theories. The chapter concludes with twenty questions intended to guide the reader in the design and use of digital textbook substitutes. © 2010 American Chemical Society.