During the 1960s, Katy Kelly and her brother, Michael, bicycled all over Capitol Hill, taught their friends how to play soccer on the Library of Congress lawn and wandered the halls of Congress in Washington, D.C.

"Michael and I were such little scavengers," said Ms. Kelly, the author of a successful series of children's books about a 9-year-old red-haired girl named Lucy Rose.

That carefree and captivating childhood inspired Ms. Kelly, a former senior editor at U.S. News and World Report, to create Lucy Rose, a self-assured girl who loves projects and challenges.

"She's a quirky kid. She listens to adults a lot, tries to imitate them and misses by a hair," Ms. Kelly said.

Long before the nation's Capitol became a maze of metal detectors and visitors' centers, Ms. Kelly and her brother visited U.S. senators, where they sought autographs and left with treats. The Vermont senator gave out maple sugar candy and the Georgia senator handed out peanuts.

"We knew, having had a mother from the South, that we were not allowed to say, 'Hi, we're here for the free peanuts,'" said the author of "Lucy Rose: Working Myself to Pieces & Bits." The fourth book in the series, which launched in 2003, is published by Knopf Delacorte Dell.

At the Kelly family dinner table, there was lots of laughter, storytelling and wisecracking, Ms. Kelly recalled. Her father, Tom Kelly, who wrote features for The Washington Daily News, emphasized the importance of original thinking.

"It was not so important to get algebra but it was important to think your own thoughts," Ms. Kelly said.

With the exception of her youngest sister, Nell, who teaches first grade, Ms. Kelly comes from a family of writers. Her mother, Marguerite Kelly, wrote "The Mother's Almanac" and still writes the syndicated column "The Family Almanac." Her sister, Meg, is co-head writer on NBC's "Days of Our Lives." Her brother, Michael, who was editor of the Atlantic Monthly and a syndicated columnist, died at age 46 while on assignment in Iraq in 2003.

Ms. Kelly dedicated the second book in the series to her brother, who is the inspiration for Lucy's friend, Adam Melon, better known as Melonhead. Her late brother's sons, 11-year-old Tom and 7-year-old Jack, "get a huge kick out of the character" and often ask, "Did Dad do that?"

Like all writers, Ms. Kelly loves words. Lucy Rose does, too, especially palindromes, which are words, phrases or sentences that read the same whether they are spelled forward or backward.

"She uses big words, not always correctly. I think kids are really into words, and television doesn't feed that very much."