Contents (view Concise Listing)

• Heavy Planet • (1939) • short story by Milton A. Rothman [as by Lee Gregor]
• Lenny • [Susan Calvin] • (1958) • short story by Isaac Asimov
• Chain Reaction • (1956) • short story by Lyle G. Boyd and William C. Boyd [as by Boyd Ellanby]
• A Feast of Demons • (1958) • novelette by William Morrison
• The Test Stand • (1955) • short story by G. Harry Stine [as by Lee Correy]
• To Explain Mrs. Thompson • (1951) • short story by R. S. Richardson [as by Philip Latham]
• Amateur in Chancery • (1961) • short story by George O. Smith
• The Mark Gable Foundation • (1961) • short story by Leo Szilard
• The Miracle of the Broom Closet • (1952) • short story by Norbert Wiener [as by W. Norbert]
• The Black Cloud (Excerpt) • (1957) • short fiction by Fred Hoyle
• Adrift on the Policy Level • (1959) • short story by Chan Davis [as by Chandler Davis]
• The Invasion • (1940) • novelette by Willy Ley [as by Robert Willey]
• The Singers • (1956) • short story by W. Grey Walter
• The Heart on the Other Side • (1962) • short story by George Gamow
• On the Feasibility of Coal-Driven Power Stations • (1956) • short story by O. R. Frisch
• Introduction (The Expert Dreamers) • (1962) • essay by Frederik Pohl
• At the End of the Orbit • (1961) • short story by Arthur C. Clarke (variant of Hate)