Common counsel to would-be writers, and sound advice it is, too. Except that it doesn't work for me. What I already know doesn't interest me nearly as much as what I want to know.

But of course, I do have to begin with what I know. I've been a baseball fan since I was nine years old, a Cubs fan first and now, almost forty years on, a Mets fan. For a long time now I have wanted to write a baseball story, but it took me a while to settle on exactly which aspect of baseball I wanted to know more about.

I finally decided to explore the nature of being a fan. The attachment fans have to their teams fascinates me. Fans develop intense relationships with people they almost never meet or speak to, people who can become almost as important to them as the friends or colleagues they see every day. What's up with that?

Keeping Score is more a story about loving baseball than it is about the game itself. I gave Maggie many characteristics of my own girlhood baseball mania. She doesn't want to play baseball. (My ball-playing skills were negligible.) She has a favorite player who's not on her favorite team. (My team was the Cubs, but I loved Roberto Clemente of the Pittsburgh Pirates.) She says prayers for the Brooklyn Dodgers (I prayed fervently for the Cubs), and wonders why her prayers don't seem to work (mine worked even less well, as anyone who follows baseball knows!).

Writing about Maggie's love for the Dodgers enabled me to explore perhaps the greatest era baseball has ever known — the post-war years. A time when the influx of players from the Negro leagues raised the quality of every aspect of the game; when players stayed with one team for all or most of their careers, enabling fans to develop long-term loyalty to them; when there was no such thing as a designated hitter to increase runs but narrow the scope of everything else. A time before steroids.

Above all, it was a time when baseball reigned unchallenged as the national game. Because of that, baseball reflected the nation itself in ways that it will probably never do again. The U.S. was at war back then, in an almost-unknown country called Korea. I knew very little about the Korean War, and I wanted to know more.

So Keeping Score is a baseball story that morphs into a war story. There are moments in the book that are among the most intense I've ever tried to depict — not surprising when you consider that sports and war are two topics that engender deeply passionate emotions. It was difficult and exhausting and ultimately very rewarding to try to render that kind of intensity. I have to say that while I have great affection for all of my books, Keeping Score is my personal favorite.

I began with what I knew, but I wrote my way through what I wanted to know. In doing so, I was privileged to spend time in Maggie's world, and I loved it there so much that it was hard to let go when it came time for the book to be published. I hope readers will enjoy exploring her world as much as I did.

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Linda Sue Park is the author of the Newbery Medal book A Single Shard, many other novels, several picture books, and most recently a book of poetry: Tap Dancing on the Roof: Sijo. She lives in Rochester, New York, with her family, and is now a devoted fan of the New York Mets. For more information visit www.lspark.com.