Lerangis's work includes the Seven Wonders series, all five books of which made The New York Times Best Seller list for Children's Books. He was also the author of The Viper's Nest and The Sword Thief, two titles in the New York Times-bestselling children's-book series The 39 Clues, along with the second entry in a four-novella collection, Vespers Rising. This book served as an introduction to a six-book 39 Clues sequel entitled Cahills Vs. Vespers, for which he wrote the third book, The Dead of the Night. He also ghost-writes for series such as the Three Investigators, the Hardy Boys Casefiles, Sweet Valley Twins, and more than forty books in the series The Baby-sitters Club and its various spin-offs. He has also written novels based on film screenplays, including The Sixth Sense, Sleepy Hollow, and Beauty and the Beast.