No, O'Connor says, "I was a cowgirl."

And that leads her to describe herself, at 79, as a "retired cowgirl, or should I say, unemployed cowgirl?"

Her book, Finding Susie (Knopf, $16.99, published today), illustrated by Tom Pohrt, is aimed at children 4 to 8. It's about the adventures and misadventures of a girl named Sandra who tries to find an animal to be her best friend.

For various reasons, neither Hercules, a desert tortoise; Daisy, a wild rabbit; Slim Pickins, a coyote; or a bobcat named Bob work out as pets. In the end, a little white dog named Susie likes Sandra's company.

"It's all true," O'Connor says, even the part about Susie smiling "at appropriate times."

The breed? "Total mutt."

It's O'Connor's second children's book. Chico (2005) is about a horse she learned to ride at age 6. O'Connor and her younger brother, H. Alan Day, wrote a 2001 best seller, Lazy B, about life on their parents' ranch.

She turned to children's books "because looking back, I realized I had such an unusual childhood that may be of some interest."

Nominated by President Reagan, O'Connor served on the Supreme Court from 1981 to 2006 as its first female member. (The second, Ruth Bader Ginsburg, joined the court in 1993.)

The court's information office says that as far as it knows, O'Connor is the first justice to write a children's book or appear on The Daily Show With Jon Stewart (in March to promote an educational website, ourcourts.org) or Late Show With David Letterman (tonight, to discuss her book).

Of Stewart's show, she says: "I'm told it's the best way to reach young people. I had so much feedback. He's intelligent and fun. We could have talked much longer."

O'Connor, who lives in Phoenix, says that she's in good health, if "creaky," but that her husband, John Jay O'Connor, 79, who has Alzheimer's disease, continues his "long, sad journey downhill."

As for Supreme Court nominee Sonia Sotomayor, O'Connor says she's "very pleased" there may be another woman on the court.

She says she doesn't know much about Sotomayor's judicial record but is impressed with her experience and education.

Is it more significant that Sotomayor is a woman or Hispanic?

"I can't say. One hopes that all of one's background affects your modus operandi. I'm a retired cowgirl. I tend to the practical."