Julie Garwood, a romance novelist whose books — some set centuries ago, some sampling present-day maladies like computer hacking and Ponzi schemes — routinely landed on best-seller lists, died on June 8 at her home in Leawood, Kan., on the Missouri border. She was 78.

Her publisher, Berkley, part of the Penguin Group, announced her death in a statement but did not specify a cause.

More than 40 million copies of Ms. Garwood’s books are in print in 32 languages, the company said. She was in her 40s when her writing career took off.

She had written but not yet published a young-adult novel, “A Girl Named Summer,” when she entered the historical romance genre in 1985 with “Gentle Warrior,” a story set in feudal England. She was prolific: “Rebellious Desire,” “Honor’s Splendor,” “The Lion’s Lady” and “The Bride” all followed before the end of the 1980s.

Her books quickly became extremely popular. But, as she often said, her real life, busy with children, kept her grounded.

“When I was in Seattle the other day, I was met at the airport by a limo,” she told The Kansas City Star in 1989, referring to a book tour. “I came home, and the laundry was unreal.”

The early adult books were all historical novels, and Ms. Garwood took pride in the research she put into them, knowing that some of her readers would be sticklers for accuracy.

“I get letters that say I’ve made an error,” she told The New York Times in 2007. “Know what I do? I send them the reference, usually three — I have to find three references before I’ll include something in a book.”

The historical details were, of course, only a side dish; the main course was romance, served in prose typical of the genre.

“The kiss was very gentle, undemanding too, until she put her arms around his neck and turned all soft and willing on him,” Ms. Garwood wrote in “The Secret” (1992) when, after a 114-page buildup, a 12th-century Englishwoman named Judith and a Scottish warlord named Iain set their simmering passions free. “He couldn’t control himself. The kiss turned hard, hot, consuming. Wonderfully arousing.”

After working the historical romance genre for 15 years, Ms. Garwood began writing contemporary novels with a strong component of suspense. The first was “Heartbreaker” (2000), which begins with a priest hearing a confession by a psychopath, not about a past crime but about a crime he intends to commit: He plans to kill the priest’s sister.

The contemporary novels, though, still had their share of heavy breathing. In her most recent book, “Grace Under Fire” (2022), when the main character, Isabel, is accidentally involved in a shooting, a dashing lawyer named Michael takes her under his wing, and a third of the way through, sparks fly.

“Before she had an inkling of what he was going to do,” she wrote, “he leaned down and, wrapping his big strong arms around her, kissed her long and hard.”

“Sweet Talk” (2012) involved an I.R.S. agent investigating a Ponzi scheme; Ms. Garwood immersed herself in the details of the Bernie Madoff scandal to write it. “Wired” (2017) was about a computer hacker — not a subject she knew much about, she told The Times, but she consulted with acquaintances to make sure she had the details right.

Some critics found her stories and characters simplistic. But she said she tried to make the women in her stories strong-minded, whatever century she put them in.

“If I have a heroine who stays with a man who is obnoxious until the last page of the book,” she told The Birmingham Post-Herald of Alabama in 1993, “then she’s not a heroine.

“She needs more work.”

Julia Elizabeth Murphy was born on Dec. 26, 1944, to Thomas and Felicita (Kennedy) Murphy and grew up in Kansas City, Mo.

Ms. Garwood often talked about not being able to read until she was 11, a consequence of missing a lot of school because of a health issue.

“I had my tonsils out in the second grade and had a lot of complications,” she told The Orange County Register of California in 1993. “When I got back to school, the other kids were reading already. I just couldn’t catch up.”

At first, she said, she did not react well to finding herself behind, and she tried to hide it from peers and teachers.

“I was so afraid they were going to find out that I was stupid,” she told the Birmingham newspaper, “that I became a behavior problem because that took the focus away. I remember being scared a lot.”

She credited a nun at St. Teresa’s Academy in Kansas City with putting her on the right path.

“Sister Elizabeth made quite an impact on me,” Ms. Garwood, who often spoke to schoolchildren about her experience, told The Star in 1997. “She started me on Nancy Drew once we had the basics. Then she moved me on to O. Henry.”

“Once I could read,” she added, “I consumed everything I could find.”

Ms. Garwood’s marriage to Gerald Garwood, in 1967, ended in divorce. She is survived by a daughter, Elizabeth; two sons, Bryan and Gerald; two sisters, Kathleen McGuire and Mary Benson; and three grandchildren.