Sam Moskowitz was a fan and historian of fandom, author of books including The Immortal Storm: A History of Science Fiction Fandom (1954) and Seekers of Tomorrow: Masters of Modern Science Fiction (1966), who began publishing anthologies in 1954 with Editor's Choice in Science Fiction, with stories selected by various magazine editors. His other couple dozen (several co-edited with Roger Elwood) appeared from the early '60s to the early '70s and often focused on early, pre-genre SF (e.g. Science Fiction by Gaslight, 1968). Most were paperback originals. Compiled here are that first anthology, and three later hardcover volumes.

The cover images here are from isfdb.