And it's not just women who buy her books. Roberts recalls hearing from a man who read "Sea Swept," one of the books in her Chesapeake trilogy. He didn't know that it was classified as a romance and initially had a problem with that. But liking the book, he came around. "Well, so what," he said.
It's OK to read for fun. That's the message of Jim Trelease, author of "The Read-Aloud Handbook," a best-selling guide to children's literature for parents and teachers.
Trelease heard about the diet Coke promotion. "Can such an idea work to promote reading in general? Worth a try, at least," was Trelease's e-mail comment while on a California vacation. He said his wife was reading a romance novel on their trip.
"Every book you pick up and read for pleasure is a celebration," Roberts says. She reads a lot - including romance novels, a genre that suited the lifestyle of a single mom with two little boys when she started writing. She could put them down for a nap, pick up a book and finish it by the time they woke up.
"I needed my reading fix," she says.
In 1979, she was living on 40 acres in southern Washington County. She's still there. Roberts moved from Montgomery County, Md., as part of what she calls the "great exodus of the '70s." "I'm the only one who stayed," she says.
Roberts was snowed in by what she calls the "blizzard of '79" when she first put pen to paper. In what began as a hobby, Roberts figured she could write a romance.
Where do the ideas come from?
"Who knows?" is Roberts' answer. "Ideas are the easiest part," she says.
She credits her success to the "three Ds": drive, discipline and desire. You can have all the talent in the world, but without those qualities, you won't make it, Roberts believes.
Writing rarely comes easily, Roberts says. "Ignorance was bliss for me," Roberts says. She made some lucky mistakes and fortunate choices. She recalls, for example, being contacted by a start-up literary agent very early in her career. Roberts signed with her without knowing much about it. She considered herself "so hot" to have a New York agent. They've been together ever since.
Later, after she was more established and her books would be considered on the basis of just an outline, Roberts learned she couldn't work that way. So she faked it for a while, writing the whole book and going back and submitting an outline.
Roberts says her characters often surprise her, taking on lives of their own. "If they don't, I'm not doing my job." She'd be telling her own story, not their story, she explains.
As a teenager, Olivia, the heroine of "River's End" says that she'd rather be smart when someone tells her she's pretty. Her characters don't mind being pretty, Roberts says. But the women she writes about also are strong or learning to be strong.
"I think it's important when you're writing for women that you respect them," she says.
Roberts likes the genre in which she writes.
"I can do anything I want with romance."
She does something a little different under the pseudonym J.D. Robb. The Robb books - there are 12 - came about at the request of Roberts' publisher.
"You have to slow down," she was told.
Roberts calls these books romantic suspense. They are set in the future - 2058 - and the heroine is a homicide lieutenant in New York. She describes them as grittier and darker than her other books, and they have "cooler toys," including the AutoChef.
"We will never cook again," Roberts says.
Roberts hears from her fans. They get very attached to the characters and try to guess what she will do next. She once heard from a woman who told her that she read her books after her mother had died and they helped her to "go away for a while."
That meant a lot to Roberts.
"You want someone to be able to put real life aside," she says.
Roberts' fans hear from her. About two years ago, Sue Noyes, who works in an independent bookstore in Danville, Pa., was looking for a new author to read. She got online and challenged the fans of Patricia Cornwell and Roberts to convince her to read one of their books.