Abstract. The location and provision of information services has dramatically changed over the last ten years. There is no need to leave the home or office to locate and access information now readily available on-line via digital gateways furnished by a wide variety of information providers, (e.g. libraries, electronic publishers, businesses, organizations, individuals). Information access is no longer restricted to what is physically available in the nearest library. It is electronically accessible from a wide variety of globally distributed information repositories-"digital libraries". In this chapter we will focus on digital libraries, starting with a discussion of the historical visionaries, definitions, driving forces and enabling technologies and some key research issues. We will discuss some of the US and international digital library projects and research initiatives. We will then describe some of the emerging techniques for building large-scale digital libraries, including a discussion of semantic interoperability, the "Grand Challenge" of digital library research. Finally, we offer our conclusions and a discussion of some future directions for digital libraries.