Terrestres e estranhos (1968), Portuguese version of Earthmen & Strangers including new Portuguese scifi texts organized by Portuguese writer and publisher Lima Rodrigues[12][13]
Men and Machines (1968)
Voyagers in Time (1967)
How It Was When the Past Went Away (1969) in: Three For Tomorrow (3 short stories by Silverberg, Roger Zelazny, James Blish, foreword Arthur C. Clarke) (1970, Victor Gollancz; 1972, Sphere Books, p.11-80)
Great Short Novels of Science Fiction (1970} SBN 345-01960-1-095 Six novellas by A. Bertram Chandler, C.M. Kornbluth, Jack Vance, Charles V. DeVet and Katherine MacLean, Wyman Guin, Roger Zelazny
Deep Space: Eight Stories of Science Fiction (1973)
Infinite Jests: The Lighter Side of Science Fiction (1974)
Robots Through the Ages (with Bryan Thomas Schmidt) (2023, Blackstone Publishing, ISBN 979-821238483-4)
Non-fiction
For adults
Sex and the Armed Services (1960, as L. T. Woodward)
Sex and Hypnosis (1961, as L. T. Woodward)
Drummond, Walter (pseud.) (1962). Philosopher of evil.
— (1963). How to spend money.
Silverberg, Robert (1965). The Great Wall of China. Chilton Books.
Cook, Roy (pseud.) (1966). Leaders of labor. Philadelphia: Lippincott.
Kublai Khan: Lord of Xanadu (1966, as Walker Chapman)
The Loneliest Continent: The Story of Antarctic Discovery (1964, as Walker Chapman)
Antarctic Conquest: The Great Explorers in Their Own Words (1966, as Walker Chapman)
The Golden Dream: Seekers of El Dorado (1967, as Walker Chapman)
Sophisticated Sex Techniques in Marriage (1967, as L. T. Woodward)
Mound Builders of Ancient America: The Archeology of a Myth (New York Graphic Society, 1968); Silverberg's fourth-most widely held work in WorldCat libraries
The Realm of Prester John (1972)
Drug Themes in Science Fiction (1974)
Reflections and Refractions: Thoughts on Science Fiction, Science and Other Matters (1997; revised & expanded edition 2016)
Silverberg, Robert (1960). Treasures beneath the sea. Illustrated by Norman Kenyon. Racine: Whitman.
Black, Edgar (pseud.) (1961). Sir Winston Churchill: the compelling life story of one of the towering figures of the 20th Century. Derby, Conn.: Monarch Books.
Silverberg, Robert (1961). First American into space. Derby, Conn.: Monarch Books.