Future Science Fiction and Science Fiction Stories were two American science fiction magazines that were published under various names between 1939 and 1943 and again from 1950 to 1960. Both publications were edited by Charles Hornig for the first few issues; Robert W. Lowndes took over in late 1941 and remained editor until the end. The initial launch of the magazines came as part of a boom in science fiction pulp magazine publishing at the end of the 1930s. In 1941 the two magazines were combined into one, titled Future Fiction combined with Science Fiction, but in 1943 wartime paper shortages ended the magazine's run, as Louis Silberkleit, the publisher, decided to focus his resources on his mystery and western magazine titles. In 1950, with the market improving again, Silberkleit relaunched Future Fiction, still in the pulp format. In the mid-1950s he also relaunched Science Fiction, this time under the title Science Fiction Stories. Silberkleit kept both magazines on very slim budgets throughout the 1950s. In 1960 both titles ceased publication when their distributor suddenly dropped all of Silberkleit's titles.

The fiction was generally unremarkable, with few memorable stories being published, particularly in the earlier versions of the magazines. Lowndes spent much effort to set a friendly and engaging tone in both magazines, with letter columns and reader departments that interested fans. He was more successful than Hornig in obtaining good stories, partly because he had good relationships with several well-known and emerging writers. Among the better-known stories he published were "The Liberation of Earth" by William Tenn, and "If I Forget Thee, Oh Earth" by Arthur C. Clarke.

Although science fiction (sf) had been published before the 1920s, it did not begin to coalesce into a separately marketed genre until the appearance in 1926 of Amazing Stories, a pulp magazine published by Hugo Gernsback. By the end of the 1930s the field was booming. One of Gernsback's employees, Louis Silberkleit, became a publisher in his own right in 1934 when he founded the Winford Publishing Company. Towards the end of the 1930s Silberkleit decided to launch an sf pulp magazine under his Blue Ribbon Magazines imprint; the title he chose was Science Fiction. Gernsback recommended Charles Hornig to Silberkleit for the post of editor; Hornig had previously edited Wonder Stories for Gernsback from 1933 to 1936. Silberkleit took the recommendation and Hornig was hired in October 1938. Hornig had no office; he worked from home, coming into the office as needed to drop off manuscripts and dummy materials, and pick up typeset materials to proof. He was given broad freedom to select what he wanted to publish; he reported to Silberkleit's chief editor, Abner J. Sundell, but Sundell knew little about sf and did not get involved with running the magazine. The first issue was dated March 1939. The schedule was intended to be bimonthly, but it began to slip immediately, with the second issue dated June 1939.

To spread his costs over more magazines, Silberkleit soon decided to launch two additional titles. When he had worked for Gernsback, Silberkleit had suggested "Future Fiction" as a possible title for the magazine Gernsback was planning to launch. Gernsback eventually chose "Amazing Stories" instead, and Silberkleit now decided to use his original suggestion for one of the new magazines. In November 1939 the first issue of Future Fiction appeared; it was followed in July 1940 by Science Fiction Quarterly. Hornig was editor for all three magazines. In October 1940, Hornig received his military draft notice; he was a pacifist, and decided to move to California and register as a conscientious objector. He continued to edit the magazines from the west coast, but Silberkleit was unhappy with the arrangement. Silberkleit allowed Hornig to retain his post as editor of Science Fiction, and offered the editorship of the other two titles to Sam Moskowitz. Moskowitz declined, saying afterwards "I would never strike at a man's job", but Donald Wollheim heard of the offer and prompted Robert W. Lowndes to write to Silberkleit. Lowndes later recalled Wollheim's idea: "In the letter, I'd suggest that it might be a good idea to add a science fiction title to the list, offering my services as editor at a slightly lower price than Hornig was being paid, and also find fault with all the other sf titles presently out, but particularly with Hornig's". Lowndes relates that Silberkleit took the bait and hired him in November 1940; Hornig recalls the separation as being by mutual consent because of his move to California. Lowndes subsequently agreed that this was likely to be the real reason Silberkleit replaced Hornig. The first issues Lowndes was responsible for were the Spring 1941 issue of Science Fiction Quarterly and the April 1941 issue of Future Fiction. He completed the preparations for the last issue of Science Fiction, dated September 1941, but he used material that Hornig had already selected for the magazine, with minor exceptions. The changes included the replacement of Fantasy Times, a fan department by James Taurasi, with Futurian Times, a similar department from a rival group of fans, the Futurians, to which Lowndes belonged. Initially Silberkleit kept tighter control on Lowndes' editorial selections than he had on Hornig's, vetoing five of the seven stories Lowndes proposed for the April 1941 Future, but by the August 1941 issue, Lowndes later recalled, Silberkleit "was satisfied that I knew what I was doing, and ... didn't need to oversee any story I had accepted".

Science Fiction was not selling well, and later that year Silberkleit merged it with Future Fiction, under the title Future Combined with Science Fiction. The last independent issue of Science Fiction was dated September 1941, and the first merged issue was dated October 1941. The final two issues of the combined magazine, dated April and June 1943, were, confusingly, titled Science Fiction Stories; this was an attempt to improve sales by reminding readers of Science Fiction, but before sales figures could be tallied to determine the impact of the title change, Silberkleit made the decision to cease publication. The June 1943 issue was the last for some years: Silberkleit was forced to cut some of his titles because of wartime paper shortages, and he decided to retain his western and detective magazines instead.

In 1950, Silberkleit brought back Future, under the title Future Combined with Science Fiction Stories; this allowed Silberkleit to keep the rights to both the titles. The first issue was dated May/June 1950. In January 1952 the title changed to just Future Science Fiction Stories. Payment rates at that time were one to three cents per word. In the summer of 1953, with Future still in pulp format, Silberkleit issued a single digest-sized magazine with no number and no date, under the title Science Fiction Stories. Another issue with the same format and title followed in the spring of 1954, also unnumbered. Silberkleit decided that the digest format was partly responsible for the good sales of these experimental issues, so he changed the format of Future from pulp to digest. The first issue in the new format was dated January 1955, and in response to reader feedback the title was changed to Science Fiction Stories. The volume numbering was continued from the existing Future volume numbering, despite the fact that the title was taken from Science Fiction, the earlier magazine. Complicating matters, Silberkleit decided later in 1955 that the market could support both titles, so he revived Future again. Since Science Fiction Stories was using the volume numbering from the previous pulp-format incarnation of Future, Silberkleit switched to an issue number format, with no volume. The first issue was numbered 28, counting forward from the May/June 1950 issue as 1.

Both Science Fiction Stories and Future Fiction were able to maintain a fairly regular schedule through the rest of the 1950s. Science Fiction Stories was bimonthly throughout, except for a brief period from mid-1958 to early 1959 when it patchily adhered to a monthly schedule. Future Fiction began with three undated issues, then switched to a quarterly schedule in 1956, and finally to a regular bimonthly schedule from the start of 1958.

With the September 1955 issue, the title graphic of Science Fiction Stories was modified so that the cover read The Original Science Fiction Stories. This was intended to make it clear that the magazine was a continuation of the 1939 version of Science Fiction, but it led to additional confusion, with some readers believing that this was an entirely new magazine. Lowndes addressed the confusion in the letter column of Science Fiction Stories, saying