Had Erin Stead made a different decision in college, A Sick Day for Amos McGee might never have existed. At the beginning and end of her college years, Stead planned to be an illustrator, but for a period in between, painting was her artistic goal. "For a while I thought I would be a serious painter, the kind that smokes cigarettes and wears a black beret," she recalls. "But then I got back to illustrating. It keeps me honest, and I'm much happier doing it."

After college, Stead worked at several bookstores, among them Books of Wonder in New York City, and spent a year as assistant to the creative director at HarperCollins Children's Books. But despite having experience in the business, she found that working on Amos McGee, written by her husband, Philip Stead (author and illustrator of Creamed Tuna Fish and Peas on Toast, 2009), was difficult in unexpected ways. "I think the reason I wasn't prepared is because drawing for me is really hard," Erin says. "Not that I don't like to do it, but it requires a lot of courage that I don't always have."

Philip Stead wrote Amos McGee knowing his wife would do the illustrations—even before she knew it herself. "Before this book, I don't think I ever actually sat down with the intention of writing a story," he says. But with Amos McGee, "I sat down at my desk and thought I'd write a story for Erin. I thought of characters specifically for her."

From Erin's perspective, events came as more of a surprise. "Neal [Porter], my editor, had bought Phil's first book and he'd heard that I illustrate, too," she says. "Neal and Phil took me to dinner—I was unaware of the story at the time—and they both asked if I'd illustrate it. I just fell into it."

The story centers on Amos, a zookeeper who spends his days helping his animal friends—until one sniffly, sneezy day when his pals find that it's their turn to help him. Erin knew from the start that she didn't want to accompany her husband's narrative with pencil drawings, and turned to woodblock printing to make her illustrations "soft and flat, and have texture, and use a limited color palette."

While she worked on Amos McGee, Erin stopped looking at other artists' work. "I didn't want to be scared, and I wanted to be honest," she says. Her favorite illustrators are Maurice Sendak and German illustrator Sebastian Meschenmoser. But the only artist from whom Stead took even the slightest inspiration for this book was Evaline Ness, whose work she used "to get to how I wanted to think about color in my drawings."

There is one illustrator, however, whose work Erin can't help surrounding herself with. For her, swapping ideas with her husband, with whom she shares a studio, is a completely natural way to work. "There are actually moments when you can see us copying each other, sometimes on paper, sometimes not," she says. "Sometimes you're just sitting at your desk, and no matter what, you just can't draw a character design," she says, citing Amos McGee's rhinoceros, which her husband helped her get started on. "I often wonder how people do this without someone with them in the studio all the time," Philip says in agreement. "We're constantly passing things back and forth to each other."

Now that her first book, which was released by Neal Porter Books at Roaring Brook Press, is out in bookstores, Erin is already working on others. Her next project, And Then It's Spring, will be published by Porter at Roaring Brook. "It's a poem written by my friend Julie Fotliano. And Phil and I are thinking about a story about a bear."

Philip Stead also has a few new projects. "In spring I have a story coming out with Roaring Brook that I wrote and illustrated, called Jonathan and the Big Blue Boat. It'll be very much in the style of my first book. And I've just completed the draft of a story that's probably for Erin, but I can't talk too much about that—my editor hasn't even seen it yet."

Asked what she'd like people to take away from Amos McGee, Erin has a ready answer. "It's up to the readers," she says firmly. "I want them to have their own experiences with it. Because I have mine."