Will there be more 39 clues books?

There are only going to be 11 books in the 39 Clues series. However, starting this August, a new series, The 39 Clues Cahills vs. Vespers, will be published. The first book, The Medusa Plot comes out soon, and the second comes out in December. After that, books will be published every March, August, and December until this sequel series is finished.