- ATID Jewish Encyclopedia - The Jewish Encyclopedia For Kids is made as an online educational site for children who are interested in Jewish facts and history.
- Bartleby.com Reference - Reference site allows you to search over the Columbia Encyclopedia, the Encyclopedia of World History, fact books, thesauri, quotes, and more.
- Children's Encyclopedia of Women - Collection of articles about famous women written by third and fourth grade students.
- Columbia Encyclopedia - 6th edition - Comprehensive online encyclopedia and database of over 51,000 entries.
- Encyclopaedia Britannica - Provides complete text of Encyclopaedia Britannica with search capabilities, related links, and multimedia enhancements. Free trial available.
- Encyclopedia Smithsonian - Links to online Smithsonian resources and answers to frequently asked questions from A to Z.
- Encyclopedia.com - Free resource offers more than 50,000 concise articles.
- EncycloZine: Learning Fun! - EncycloZine is a concise illustrated encyclopedic portal covering a wide range of topics in the arts, humanities, sciences, and technology. It also features games, puzzles, quizzes, and a multimedia gallery.
- How Stuff Works - Articles explain how hundreds of things work, from elements of the human body to space-age technology.
- Instrument Encyclopedia - A guide to more than musical 140 instruments from all parts of the world. Includes photographs and descriptions.
- MSN Encarta Encyclopedia - Online home of the Encarta encyclopedia, world atlas, dictionary, thesaurus, multimedia collection, and homework tools.
- Open Site - A volunteer-run open content encyclopedia, inspired by the Open Directory Project.
- Spartacus Educational - British online encyclopedia focuses on historical topics. Articles are geared toward students.
- TechEncyclopedia - Contains descriptions and definitions of more than 14,000 computer terms and concepts.
- VetCentric Encyclopedia - Find articles on animal health care topics ranging from behavior and preventive care to common and not-so-common diseases.
- Wikipedia - Free volunteer-edited encyclopedia with over 200,000 articles.
- wordIQ.com - An online encyclopedia with more than 400,000 pages of content.
- World Book Encyclopedia - Offers in-depth information on a variety of subjects and educational activities for children.