There are 4 books in the Improper Princesses series.
The Improper Princesses series does not have a new book coming out soon. The latest book, The Highlander's Princess Bride (Book 3), was published in November 2017.
The first book in the Improper Princesses series, My Fair Princess, was published in September 2016.
The Improper Princesses series primarily falls into the Historical Romance genre.