Second Stage Lensmen is a science fiction novel by author Edward E. Smith. It was first published in book form in 1953 by Fantasy Press in an edition of 4,934 copies. The novel was originally serialized in the magazine Astounding beginning in 1941. Second Stage Lensmen is the fifth volume in the Lensman series, and the last to feature Kimball Kinnison as the most powerful Lensman in the service of the Galactic Patrol. Second Stage Lensmen also features the first female Lensman, Clarissa MacDougall. The story mainly focuses upon the exploits of the "Second Stage" Lensmen: those who have gone through the advanced Arisian training Kinnison underwent in Galactic Patrol. These four superior Lensmen, Kinnison, Worsel, Tregonsee, and Nadreck, are armed with mental powers allowing them to control the minds of others and see, hear, and feel without using their physical senses. This elite cadre allows Civilization to tip the balance against Boskone as Second Stage Lensmen abilities are ideally suited to spying and information gathering.

Edward Elmer Smith was an American food engineer and science-fiction author, best known for the Lensman and Skylark series. He is sometimes called the father of space opera.