She was born Beatrice Leila Eliott Burton and grew up in Old Westbury, Long Island, New York. Her father, Frank V. Burton Jr., inherited his business in the cotton trade. Her middle name, which she took as her first name, was pronounced "LEE-la" and was, according to her, "Hindi for 'cosmic play,' which should register in anyone’s mind forever, but doesn't". She attended the Green Vale School, Long Island, with Gloria Vanderbilt, then St. Timothy's School, Catonsville, Maryland. She was introduced to society at the Junior Assembly on December 23, 1943, held at the Ritz-Carlton Hotel in Manhattan.
Marriages and divorces
She married Arthur Twining Hadley, Jr., a Lieutenant in a Tank destroyer battalion, and the son of Arthur Twining Hadley, president of Yale University, on March 2, 1944. After the birth of her son, Arthur Twining Hadley III, in February 1945, her one and a half year marriage ended in divorce.
Hadley obtained employment in public relations, first working for cartoonist Al Capp and was described in a 1950 article in Look magazine as "the chic, high-level, in-the-know, celebrity-surrounded career girl that millions of young women dream of becoming in New York." She later was publicity director for The Howdy Doody Show.
In 1953 she married inventor and geologist , Yvor Hyatt Smitter. This marriage lasted 12 years. They divorced in 1968, after having three children.
In 1969, she married Swedish immigrant, Hans Gillner, car salesman and 16 years her junior (marriage later annulled as she was getting divorced from her fourth husband, William C. Musham). In 1976 she married businessman William C. Musham, that ended in divorce in 1978. January 1990 she married her fifth husband (technically her fourth since the Gillner marriage was annulled), Henry Luce III. That marriage lasted until Luce's death in September 2005..
Trip around the world
She quit her job in 1951 and took her son, then six years old, on a trip around the world that lasted one and a half years. She sailed on a barkantine schooner from Singapore to Ceylon, then from Beirut to Malta. It was on the schooner where she met geologist, Yvor Hyatt Smitter, the son of author, Wessel Smitter. S. J. Perelman, who urged her to take the trip in the first place, then encouraged her to write Give Me the World (1958) about her journey.
After returning to America and marrying Smitter on 24 January 1953, she lived in South Africa, then in Jamaica, then in the West Indies. She worked at Diplomat magazine in 1966 and at The Saturday Evening Post as cartoon editor in 1968-69. She wrote a number of books, including How to Travel With Children in Europe (1963), Fielding's Guide to Traveling with Children in Europe (1972) and Traveling With Children in the U.S.A. (1976). She co-wrote the 1966 book Manners for Young People with John Barclay, who gave dancing lessons to children at the Pierre Hotel. She and Smitter had three children before they divorced in 1969.
India and A Journey With Elsa Cloud
She visited her daughter, Victoria Barlow, who was living in Dharamsala, India, where she had been studying Buddhism at the Library of Tibetan Works and Archives and in Manali, in meditation retreat. The trip became the inspiration for her book A Journey With Elsa Cloud, which provided a fictionalized account of her own experiences. The book's title was derived from the private name, elsa cloud, her daughter created as a fifteen year old runaway, when she daydreamed she would like to be the sea or else a cloud; elsa cloud. Her daughter denounced the book.
The trip triggered an interest in Tibetan people. She became a member of the board of Tibet House and her experiences on her trip became the source of her 1979 pamphlet Tibet 20 Years After the Chinese Takeover.
In 1975, she married businessman William Musham; the marriage ended in divorce less than three years later, due in part, according to Musham's son, to Hadley's "decadent" behavior and lifestyle. On January 5, 1990 she married  Henry Luce III, son of Henry Robinson Luce, the co-founder of Time Magazine and head of The Henry Luce Foundation. The couple remained together until his death in 2005.
Lawsuit; sued by her daughter and granddaughter
In a lawsuit filed in May 2003 , Hadley's daughter, Caroline Nicholson, stated that Leila Hadley Luce and Henry Luce III, who died ten days before being deposed, were continuing a prior pattern of committing incest and child sexual abuse of Caroline in the 1970s by sexually abusing Caroline's daughter, their granddaughter, in the 1990s. Caroline claimed that Luce had repeatedly tried to rape her, sexually abused her over a six year span, and that she had been lured into bed by Luce and her mother. Hadley denied the allegations, and insisted that the suit had been an attempt to obtain money from her. The case was due to go to trial on January 12, 2009 but was settled out of court eight weeks before Hadley died.
Hadley, who had suffered from emphysema for several years, died at age 83 on February 10, 2009 at her Manhattan home. She also lived on Fishers Island, New York, where she is buried next to Henry Luce III at the Union Chapel. She was survived by her eldest son, Dr. Arthur T. Hadley III, Matthew Eliott (who had changed his last name from Smitter in the 1970s), Caroline Nicholson, Victoria California Van Duzer Barlow, stepson Henry Christopher Luce, stepdaughter Lila Luce, and six grandchildren.