Contents (view Concise Listing)

• ix • Introduction (Invaders of Earth) • (1952) • essay by Groff Conklin
• 1 • Prologue: The Distant Past • (1952) • essay by uncredited
• 2 • This Star Shall Be Free • (1949) • novelette by Murray Leinster
• 21 • Part One: The Immediate Past: It Could Have Happened Already • (1952) • essay by uncredited
• 22 • Castaway • (1941) • short story by Robert Moore Williams
• 37 • Impulse • (1938) • short story by Eric Frank Russell
• 48 • Top Secret • (1948) • short story by Donald A. Wollheim [as by David Grinnell]
• 50 • An Eel by the Tail • (1951) • short story by Allen Kim Lang [as by Allen K. Lang]
• 61 • A Date to Remember • (1949) • short story by William F. Temple
• 75 • Storm Warning • (1942) • short story by Donald A. Wollheim [as by Millard Verne Gordon]
• 86 • Child of Void • (1949) • short story by Margaret St. Clair
• 100 • Tiny and the Monster • (1947) • novelette by Theodore Sturgeon
• 134 • The Discord Makers • (1950) • short story by Mack Reynolds
• 146 • Pen Pal • (1951) • short story by Milton Lesser
• 160 • Not Only Dead Men • (1942) • short story by A. E. van Vogt
• 181 • Part Two: The Immediate Future: It May Happen Yet • (1952) • essay by uncredited
• 182 • Enemies in Space • (1952) • short story by Carl Grunert (trans. of Feinde im Weltall? 1907) [as by Karl Grunert]
• 193 • Invasion from Mars • [H. G. Wells' War of the Worlds Universe] • (1938) • novelette by Howard Koch (variant of The Invasion from Mars: A Radio Adaptation)
• 215 • Minister Without Portfolio • (1952) • short story by Mildred Clingerman
• 223 • The Waveries • (1945) • short story by Fredric Brown
• 245 • Crisis • (1951) • short story by Edward Grendon
• 255 • Angel's Egg • (1951) • novelette by Edgar Pangborn
• 290 • "Will You Walk a Little Faster?" • (1951) • short story by William Tenn (variant of "Will You Walk a Little Faster")
• 301 • The Man in the Moon • (1943) • short story by Henry A. Norton
• 311 • Pictures Don't Lie • (1951) • short story by Katherine MacLean
• 329 • Epilogue: The Distant Future • (1952) • essay by uncredited
• 330 • The Greatest Tertian • (1952) • short story by Anthony Boucher