American general encyclopaedia, published in Danbury, Conn., by Grolier, Inc., the second largest encyclopaedia in English and the first major multivolume encyclopaedia published in the United States.

First published in 1829–33, with subsequent editions in 1911 (20 volumes) and 1918–20 (30 volumes), and thereafter continuously revised, Americana is international in scope and is known for its detailed coverage of American and Canadian geography and history. It is also strong in biography and scientific and technical subjects. All major articles are signed, many by scholars preeminent in their fields.

Because of its continual volume-by-volume revision, some parts of the set are inevitably less current than others. The last complete revision and total resetting occurred in 1918–20, and that edition became the basis for its successors. The alphabetical index (volume 30) is kept up to date with each printing, however, and serves as an instructional as well as an updating device.

Other organizational aids include tables of contents for lengthy articles and information boxes that highlight specific data. Special features include numerous glossaries; separate articles evaluating particularly important literary, artistic, and musical compositions; and separate articles summarizing world, and particularly Western, history and culture for each century AD.

Americana's publisher, Grolier, Inc., is one of the largest U.S. publishers of general encyclopaedias. Grolier also publishes Encyclopedia International, The New Book of Knowledge, and Academic American Encyclopedia, the latter available in both print and electronic versions.