Space Cadet is a 1948 science fiction novel by Robert Heinlein about youngsters who join the patrol that keeps the peace in the solar system. From the space academy with a blind (but not unseeing) commandant to lessons in using a powered space suit; from discussions on ethics and responsibility to lessons in math and foreign cultures, this is a very believable schoolboy tale. Some of the issues include behavior in military and paramilitary organizations, and ethical issues common in young men. Matt and his friends avert possible war with the Venerians with some deft cultural maneuvering when a former schoolmate provokes the otherwise peace-loving matriarchical society of Venus. There is also the mention of how different an alien socety built on entirely different precepts is.

This juvenile novel inspired Joseph Lawrence Greene of Grosset and Dunlap to develop the Tom Corbett Space Cadet series of TV shows that was so popular in the early 1950s, as was the comic books, comic strips, novels and radio plays that were associated with it. Greene had originally submitted a radio script for "Tom Ranger" and the "Space Cadets" on January 16, 1946, but it remained unperformed when Heinlein's novel was published.

• June 1948, Scribner, library binding, ISBN 0684124289
• August 12, 1978, Del Rey, paperback, ISBN 0345260724
• February 12, 1982, Del Rey, paperback, ISBN 0345306317
• October 12, 1985, Del Rey, paperback, ISBN 0345333977
• October 12, 1987, Del Rey, paperback reissue edition, ISBN 0345353110
• June 1, 2003, Thorndike Press, hardcover largeprint, ISBN 078625484X

A space cadet is somebody who deals with reality in a way consistent with them being under the influence of (or "spaced out" on) drugs (slang).