While at the Tribune, she wrote a popular syndicated advice column for teenagers that later was covered by her younger sister, Sheila John Daly.

She was one of the four Daly sisters (Maggie, Kay, and Sheila John) whose successful careers in media, fashion and business were covered by national magazines during the 1940s and 1950s.

The following year, when Daly was 16, she won first prize in the same Scholastic competition with her story "Sixteen" about a girl who meets a boy at a skating rink.

It drew critical praise, including an essay by Orville Prescott in The New York Times placing Daly in a group of literary "Rising Stars" alongside Eudora Welty, Nelson Algren, Howard Fast, Mary O'Hara and others.

Seventeenth Summer became a bestseller, remaining continuously in print for over six decades and selling over 1 million copies by the time of Daly's death in 2006.

Daly explained in later interviews that she did not know Seventeenth Summer would be so successful and she needed a secure job in order to help support her mother and sisters, her father having died in 1944.

She had gained journalism experience while in college, including writing an advice column for teenagers that appeared in the Chicago Tribune and was syndicated to other newspapers.

Daly met William P. McGivern, Bill, at a book signing event for Seventeenth Summer in 1942, and corresponded with him during World War II.

In 1950, the couple decided to become freelance writers, move to Europe with their young daughter, and travel around the world, and Daly resigned her editor position with Ladies' Home Journal.

Daly (as Maureen McGivern) and her husband later co-wrote Mention My Name in Mombasa; the Unscheduled Adventures of an American Family Abroad (1958), a memoir of their travels during this time to France, Spain, Gibraltar, Iceland, Belgium, Morocco, Nigeria, and Ireland.

However, Daly was motivated to write two more novels after her husband Bill McGivern and their adult daughter Megan both died of cancer within one year of each other in the early 1980s.

Starting in 1988 and continuing into the 1990s, Daly was a long-term columnist for The Desert Sun newspaper in Palm Springs, California, writing food and restaurant reviews.

[5] In addition, Daly has been credited with completing William P. McGivern's final novel A Matter of Honor (1984) after he died in 1982 leaving it unfinished, but her name does not appear as co-author on the published editions.