Tom Swift Jr. is the central character in a series of over thirty science fiction adventure novels for male adolescents, following in the tradition of the earlier Tom Swift ("Senior") novels. The series was titled The New Tom Swift Jr. Adventures. Unlike the Nancy Drew and Hardy Boys titles that were also products of the prolific Stratemeyer Syndicate, the original Tom Swift stories were not rewritten in the 1950s to modernize them. It was decided that the protagonist of the new series would be the son of the earlier Tom Swift and his wife, Mary Nestor Swift; the original hero continued as a series regular, as did his pal Ned Newton. The covers were created by illustrator J. Graham Kaye. Covers in the later half of the series were mostly by Charles Brey. A total of 33 volumes were eventually published.

For the Tom Swift Jr. series the books were outlined mostly by Harriet (Stratemeyer) Adams, head of the Stratemeyer Syndicate, attributed to the pseudonymous Victor Appleton II, and published in hardcover by Grosset & Dunlap. Most of the books (Titles #5-#7 and #9-#30) were written by James Duncan Lawrence, who had an interest in science and technology and was faithful to the canon of the previous Tom Swift series. Title #7, Tom Swift and His Diving Seacopter, has several references to the first series, including a visit with Mrs. Baggert, who was Tom Sr.'s housekeeper, and other volumes feature a rocket named after the old family retainer Eradicate "Rad" Sampson, a radiation-detector (the Damonscope) named after Tom Sr.'s friend Mr. Damon, and a planetoid named in honor of Tom Swift Sr.'s father Barton. As in the original series, the basic locale is the quaint town of Shopton, New York, on Lake Carlopa.

Typical story elements include Tom's loyal and quip-prone friend Bud Barclay, his comic-relief cook "Chow" Winkler, a spy (typically from Soviet stand-ins Brungaria or Kranjovia), use of a wonder-material called Tomasite that did anything the story needed, the amazingly versatile force-ray repelatron, and atomic-powered everything, including the atomicar. The first invention of the series and the one making the most frequent appearances in subsequent stories, the Flying Lab (named Sky Queen), was a giant VTOL research airplane the size of a Boeing 747 jumbo jet.

The Tom Swift Jr. stories had stronger science-fiction elements than the earlier series, particularly in the later volumes. One subplot, beginning on the first page of the first volume and running the length of the series, is Tom's communication, via mathematical "space symbols", with beings from "Planet X". This mystery is never completely resolved, despite the beings sending a sample of life forms from their planet in book #7 and an artificial "energy brain" to occupy a robot body built by Tom in book #17 (see illustration above).

The stories offered science that was more intriguing than accurate. Yet the characters and titles are well-remembered and lovingly regarded, and Apple's Steve Wozniak claims to have been inspired onto his career path by Tom Swift Jr.^{[citation needed]}

The series also offers a good many recurring characters of lesser rank, in contrast to the original series. Most are Swift Enterprises employees, such as Harlan Ames, Phil Radnor, Hank Sterling, Arvid Hanson, Slim Davis, George Dilling, Art Wiltessa, and Miss Trent — the two Toms' office secretary and the lone female among recurring Swift Enterprises characters.

The first 17 titles were released in a blue tweed cloth cover with a full color paper jacket. Volumes 1–18 were also published in a blue-spined picture cover edition with Tom Swift and the Electronic Hydrolung (in its first printing only) the only title with the picture cover imprinted directly on the "boards" and wrapping around the spine, rather than as a removable dust jacket. The "blue spine" editions lasted about a year and then the entire run of Tom Swift Jr. books was reproduced in yellow spine versions and all later titles were released in this format. The Hardy Boys books (another series from the Stratemeyer Syndicate) was also released in a blue spine version; this may have prompted the change in color.

A few of the early titles of the Tom Swift Jr. series were re-released in the 1970s in paperback with new illustrations. In 1972, four (#14, #15, #16, and #17) were released as trade paperbacks. #14 was retitled Tom Swift in the Jungle of the Mayas and #15 was renamed Tom Swift and the City of Gold. In 1977, six (#1–4, #6, and #8) were released as mass market paperbacks. One of the stories, #6 Tom Swift and His Outpost in Space was renamed Tom Swift and His Sky Wheel and repositioned as #5.