Young Adult (or YA) fiction is booming. And YA books are often ranked as the most requested genre by agents. So what makes a novel both young adult and really good? Those are some of the questions I pose to my guest Marietta Zacker, who knows YA inside and out. As a partner at the Gallt and Zacker Literary Agency, she works with some of the best novelists and illustrators working today. Listen to her take on what works and what doesn't, and tips for penning your own YA masterpiece.