Consisting of more that 80 libraries, the Harvard online system is a gateway to the extraordinary library resources of Harvard University and serves as an important research tool for students, faculty staff, researchers and simple guests as well. Its OPAC (HOLLIS) is a growing database containing over 9 million electronic records out of a total of 15.8 million library holdings (books, journals, manuscripts, government documents, maps, music scores, multimedia files) with a free, unlimited access to the basic functionalities of an electronic library. The database is updated continually as material is received and catalogued. All bibliographic records are freely retrievable by using one of the three search options offered. The E-Research@Harvard Libraries website provides access to a wide variety of online sources, including digitized collections and indexes, the full text of many scholarly journals and newspapers, web guides, etc. Access to this material is mainly restricted to authorized members of the Harvard community. The catalogue section devoted to digital resources is a growing collection of web materials, which may be more or less fully retrievable according to the original source’s policy. They are regularly stored and classified with metadata and source’s address indication. Several navigational aids posted throughout the site help users’ orientation and search.