Krulik is the author and creator of several book series, beginning with Katie Kazoo, Switcheroo in 2002. The How I Survived Middle School series launched in June 2007. In July 2008, Grosset and Dunlap (a division of Penguin Young Readers) launched the George Brown, Class Clown series, a spin-off of Katie Kazoo, with the book Super Burp. Her mystery series for kids, Jack Gets a Clue launched in 2011. In 2013, she published the Magic Bone series, which follows the adventures of Sparky, a sheepdog puppy, who travels the world thanks to the magic he finds in a very special chew toy. The first two books in the series: Be Careful What You Sniff For and Catch that Wave were published in May. Krulik followed that series with Project Droid, a science fiction series of six books written with her daughter Amanda Burwasser, The Kid From Planet Z (a young chapter book series about a family who crashes down on earth and must follow the instructions of their leader, a talking cat named Zeus), and Princess Pulverizer, a series about a princess who wants to be a knight and must go on a Quest of Kindness to prove that she is up to the task. Along the way Princess Pulverizer meets up with a dragon who uses his fire to make grilled cheese, and a timid knight-in-training who has been nicknamed Lucas the Lily-Livered.