This is a list of all Hardy Boys books published, by series.
The Mystery Series consists of the first 58 stories and the Detective Handbook which were originally published between 1927 and 1979. The first 38 books and the Detective Handbook were revised between 1959 and 1973.
This now-discontinued series of paperbacks started in 1979 as a continuation of the hardcover books, hence the volume numbers start as #59 and ended in 2005 with volume 190.
In 2005, Grossett & Dunlap released hardcover versions of volumes 59 through 66. These volumes were in the blue glossy flashlight cover format, similar to the original 58 covers. The artwork on these books was from the original Wanderer paperback covers, although severely cropped to fit the covers. To date, there is no news about plans for further Grossett & Dunlap hardcover versions.
In March 2013 Grossett and Dunlap discontinued publication of Volumes #59-#66 in hardcover.
The Hardy Boys Casefiles were the first major spin-off of the Hardy Boys series that either took place after #190 Motocross Madness of the Mystery Stories line, or took place in a different continuity altogether, due to the death of Iola Morton occurring in book #1 Dead On Target. The Casefiles universe also had its own spin-offs, similar to the Nancy Drew and Hardy Boys Be-A-Detective books from the main series, but this series spin-offs were A Nancy Drew And Hardy Boys SuperMystery ('88) (with the '88 being attached by fans in 2007 to differentiate this series from a similarly named series that began in 2007) and A Hardy Boys and Tom Swift Ultra Thriller.
From 1998 to 1999, Simon & Schuster published three Hardy Boys Casefiles Collector's Editions that contained three previously published Casefiles stories (Vol. 1 #'s 38, 39 and 40; Vol. 2 #'s 48, 51 and 52; Vol. 3 #'s 55, 58 and 59). In 2005, Simon & Schuster reprinted Vol. 3 in hardcover with a different cover that used the current Hardy Boys Mystery Stories (Digest) cover of a file folder with modified art from Hardy Boys #152, exclusively for Borders Bookstores.
The Canadian rights to the Casefiles and its spin-offs have been held by Paperjacks (April 1987-December 1989) and Distican, Inc./Simon & Schuster Canada (January 1990 – present; Simon & Schuster US bought out Distican in 2002 and just changed the company name). Aside from inserting an ad for their 'Books By Mail' program, their address on the copyright page, and a small Maple Leaf with "Printed In Canada" being put on the front covers, and distributing the books, Paperjacks was allowed no other editorial/layout changes to the books. Once Distican took over the rights in January 1990, the books were all published in the US and just distributed by Distican in Canada with no publishing occurring in Canada.
Simon & Schuster UK have published many 2-in-1 and 3-in-1 books of the Casefiles since the early 1990s in the UK and other British Commonwealth Nations (except Canada). In 2005/06 Simon & Schuster UK reissued four Casefiles under the Undercover Brothers label, with two other books being planned but cancelled before publication.
Armada/Collins held the UK/British Commonwealth (except Canada) rights to the Casefiles from about 1988 till 1991, with reprint rights continuing on throughout the 1990s, allowing Armada to publish different 2-in-1 and 3-in-1 books of the first 10 Casefiles.
The Clues Brothers books were aimed at younger readers, particularly in third and fourth grades. The series was introduced in 1997 and was cancelled in 2000 for lack of popularity. Starting in 2013 the series will be available as ebooks.
This series had some big differences from the other Hardy Boys books, such as:
This series is written in first-person narrative style with Frank and Joe alternating chapters.
Spy Set - Box set of volumes 1–4 (2005)
In 2011, Simon & Schuster announced it would cancel the Undercover Brothers series and launch a new series, Hardy Boys Adventures, publishing four volumes in 2013. The series is scheduled to publish new titles three times a year. This series is written in the first person with chapters alternating between Frank's and Joe's narration. This is the first series to be available in three different formats; paperbacks, hardcover books with dust jacket, and eBooks. The first four titles had an initial printing of 25,000 copies in paperback and 2,500 copies in hardback. The fifth, sixth and seventh titles had an initial print run of 25,000 in paperback and 5,000 in hardback. 
(A new graphic novel series from Papercutz)
The Hardy Boys (Secret Files) is a series begun in 2010 by the publisher Simon & Schuster under their Aladdin imprint. It features the Hardy Boys, Frank and Joe, as grade-school detectives. Three new titles are published yearly as paperback books and eBooks.
In these books the reader controls the outcome of the story by choosing different options of advancing the plot, similar to the Choose Your Own Adventure books.
The two volume Ultra-Thriller series is a short-lived Hardy Boys spin-off that joined boy inventor Tom Swift with the crime-solving Hardy Boys, Frank & Joe. Although the Franklin W. Dixon pseudonym was used, the series was more akin to the then-current Tom Swift IV series and listed in the Tom Swift books as part of that series. Published as mass market paperback books under the Archway imprint of Simon and Schuster.
The Nancy Drew and the Hardy Boys Super Mystery books are a new series first published in June 2007 and are not to be confused with the Nancy Drew and Hardy Boys SuperMystery series that was published between 1988 and 1998.
This is a spin-off series of the Nancy Drew: Girl Detective series and The Hardy Boys: Undercover Brothers series. Books are narrated in the first person with chapters alternating between Nancy's, Frank's, and Joe's view. Series cancelled when Nancy Drew, Girl Detective and Hardy Boys Undercover Brothers series ceased publishing new titles.
There have been many Hardy Boys spin-off books and minor series over the years.
Not to be confused with The Hardy Boys Detective Handbook, The Hardy Boys Handbook: Seven Stories of Survival was first published in 1980 by Wanderer Books (an imprint of Simon & Schuster) and contains seven short stories with instructions for wilderness survival, 134 pages long. Written and illustrated by outdoor journalist and survival instructor Sheila Link under the Hardy Boys imprint, published in hardcover in different format than the rest of the series.
The first Nancy Drew and the Hardy Boys Super Sleuths book was published in 1981 with the sequel published in 1984. Both volumes contain seven short stories with Nancy Drew and the Hardy boys working together and are written under the pen-name of Carolyn Keene and Franklin W. Dixon. Both books were published under Simon & Schuster’s Wanderer Books imprint.
This book was first published by Wanderer Books in 1984 and like the Super Sleuth books, Carolyn Keene and Franklin W. Dixon listed as co-authors. National Director of Program Services, Camp Fire, Inc, Karen W. Bartz wrote a foreword for this book. Carolyn Keene and Franklin W. Dixon also wrote a foreword.
This was first published in 1984 by Simon & Schuster under their Wanderer Books, and then in 1987 by their Minstrel Books imprint. In 2002 it was published yet again by another Simon & Schuster imprint; Aladdin paperbacks. Because there were so many re-prints, several (four) different editions with different cover art exist.