Astounding Science Fiction January 1950 (Volume 44, Number 5)
Illustrations by Ed Cartier, Jack Gaughan, Paul Orban, Hubert Rogers, Ward. Cover by Chesley Bonestell.

Stories: "The Xi Effect" by Philip Latham (Robert S. Richardson)
"Undesirable Alien" by David McCarthy
"Gypsy" by Poul Anderson.

Novelettes: "Not to be Opened-" by Roger Flint Young
"Old Mother Methuselah" by René Lafayette (L. Ron Hubbard - "Ole Doc Methuselah" series.)

Article: "Maxwell's Demon and Monsieur Ranque" by Arthur C. Parlett.

Serial: "…And Now You Don't" (conclusion) by Isaac Asimov ("Foundation" series; formed middle/end of Second Foundation.)

John W. Campbell's editorial is "The Real Pushbutton Warfare." Book review by Alden Lorraine.