Kreton (Jerry Lewis) is an alien from outer space who is fascinated by human beings. Against the wishes of his teacher, he repeatedly visits Earth. During his latest visit his teacher reluctantly agrees to allow him to stay and study the humans. He becomes friends with a suburban family and stays with them, after they agree to keep his alien status a secret. Along the way he falls in love with their daughter (Joan Blackman), however, there is a force field around him that prevents any physical contact as his race has abolished any form of affection.
After repeatedly breaking the one rule from his teacher, which is not to get involved in the humans' lives, he is stripped of all his powers so that he can realize that being human isn't always happy: it comes with other less desired emotions such as pain, sadness and jealousy. Once his cover is blown on Earth and he is reported to the police, he decides that those emotions are not worth the trouble and he returns to his own planet .
Visit to a Small Planet was filmed from April 28 through July 3, 1959.