- The Maze of Bones by Rick Riordan (September 3, 2008)
- One False Note by Gordon Korman (December 3, 2008)
- The Sword Thief by Peter Lerangis (March 3, 2009)
- Beyond the Grave by Jude Watson (June 2, 2009)
- The Black Circle by Patrick Carman (August 11, 2009)
- In Too Deep by Jude Watson (November 3, 2009)
- The Viper's Nest by Peter Lerangis (February 2, 2010)
- The Emperor's Code by Gordon Korman (April 6, 2010)
- Storm Warning by Linda Sue Park (May 25, 2010)
- Into the Gauntlet by Margaret Peterson Haddix (August 31, 2010)
- Vespers Rising by Rick Riordan, Peter Lerangis, Gordon Korman and Jude Watson (April 5, 2011)
- Card Pack 1: Secrets and Sabotage
- Card Pack 2: Branch vs. Branch
- Card Pack 3: The Rise of the Madrigals
- Card Pack 4: Ultimate Card Pack
There are two ways to obtain status having the books for both series on the 39 Clues website:
- If you have the books which come with cards, you can enter the codes for the book cards in the 'My Cards' section and you will qualify as having your books.
- If you have the books in eBook format or they just didn't come with any cards, you can go to www.the39clues.com/getyourcards and prove you have the book by typing in one of the early words (which number word is randomized) in two of the book's chapters (which chapter is randomized). If you are correct, you will qualify as having your books and get the book cards, hence the address name.
- Books 1, 2, and 3's covers seem to be connected. On the following reasons:
- On The Maze of Bones' cover, shards of glass can be seen on its rightmost side.
- On the One False Note's cover, bones can be seen on the leftmost side and ninja weapons can be seen on the rightmost side.
- On The Sword Theif's cover, shards of glass can be seen on its leftmost side.
- Books 4, 5, and 6 have a map as the background.
- Books 7 and 8 have a pipe pattern as the background.