"Homo Sol" was the nineteenth story written by Asimov, the eighth to be published, and the second to appear in Astounding, which was then the world's leading science fiction magazine.

The Solarians (meaning humans, also referred to as Homo Sol) have developed hyperspace travel and landed on a planet of Alpha Centauri, thus qualifying for acceptance into the Galactic Federation of intelligent humanoid species.

The delegation returns in despair; not only have the Solarians refused the invitation, but they exhibit irrational and war-like behavior that contravenes the sacrosanct psychological laws established over millennia by Federation psychologists.

Asimov wrote "Homo Sol" in December 1939, after becoming certain that he would receive good grades in his first semester as a Columbia University graduate student.

"Homo Sol" also first mentioned the concept of psychology being developed into a mathematically rigorous science, an idea he called psychohistory in his Foundation stories.