Beyond Thirty is a short science fiction novel by Edgar Rice Burroughs. It was written in 1915 and first published in All Around Magazine in February 1916, but did not appear in book form in Burroughs' lifetime. The first book edition was issued by Lloyd Arthur Eshbach's Fantasy Press fanzine in 1955; it then appeared in the collection Beyond Thirty and The Man-Eater, published by Science-Fiction & Fantasy Publications in 1957. The work was retitled The Lost Continent for the first mass-market paperback edition, published by Ace Books in October 1963; all subsequent editions bore the new title until the Bison Books edition of March 2001, which restored the original title.
The novel, set in the year 2137, was heavily influenced by the events of World War I. In the future world depicted in the novel, Europe has descended into barbarism while an isolationist and politically united Western Hemisphere remains sheltered from the destruction. The title Beyond Thirty refers to the 30th meridian west that inhabitants of the Western Hemisphere are forbidden to pass.