This retrospective series of annual anthologies, published by DAW from 1979 to 1992 at a rate of about two per year, covered the years 1939 to 1963, to fill the gap between Asimov's earlier anthology Before the Golden Age (covering 1931 to 1938) and the first of Donald A. Wollheim & Terry's Carr's World's Best Science Fiction anthologies for Ace in 1965 (covering 1964). Greenberg did most of the work, assembling lists of candidate stories, writing book introductions that contrasted events in "the world outside reality" [i.e. the real world] with events in "the real world" [i.e. within science fiction], and providing a bibliographic introduction for each story; Asimov made final story selections, and provided personal, paranthesized, comments to each story that followed Greenberg's introductions. (Some first choices were unavailable, e.g. several Heinlein stories selected for the 2nd and 3rd volumes are noted but not included.) Contents in each volume are arranged chronologically by original publication within the year. The series ended as planned (not because of Asimov's death in 1992).