Three of Asimov's other books—Pebble in the Sky, The Stars, Like Dust, and The Currents of Space—are set in the universe of The Foundation Trilogy but at a much earlier time, when the Galactic Empire is at its height. Pebble in the Sky is a great favorite with science-fiction readers, but these works have little of the stature of The Foundation Trilogy.

Foundation's Edge is a direct sequel to the trilogy and the first novel-length treatment of the Foundation. Asimov expands the scope of the Foundation stories to include not only the Galactic Empire and the Seldon Plan but Earth as well. The novel also includes references to Asimov's Robot stories and to his novel The End of Eternity, linking much of his principal fiction together. A later novel, Robots and Empire, tells the story of the founding of the Galactic Empire...