She and her sister Carly Simon were a folk duo in the 1960s. Years later, she wrote the Tony-nominated music for “The Secret Garden.”Lucy Simon, who with her sister Carly began performing and recording as the Simon Sisters during the folk revival of the 1960s, and who then almost three decades later became a Tony Award-nominated composer for the long-running musical “The Secret Garden,” died on Thursday at her home in Piermont, N.Y., in Rockland County. She was 82.Her family said the cause was metastatic breast cancer.Ms. Simon was the middle of three musical sisters. Her younger sister, Carly, became a best-selling pop star after their folk-duo days, and her older sister, Joanna, was an opera singer with an international career. Joanna Simon, at 85, died in Manhattan a day before Lucy Simon’s death.Lucy and Carly started singing together as teenagers. Their father, Richard, was the “Simon” of Simon & Schuster, the publishing house, so a heady list of guests came through the household, including Richard Rodgers and Oscar Hammerstein II. Their mother was Andrea (Heinemann) Simon.“We would go to cocktail parties and bring our guitar and sing,” Lucy Simon told The New York Times in 2015. “And people loved it.”Eventually, she added, they said to each other, “Let’s see if we can pay our way by singing.”Carly was a student at Sarah Lawrence College and Lucy was studying at the Cornell University-New York Hospital School of Nursing in New York in the early 1960s when, during summer break, they took a bus to Provincetown, Mass. (They had wanted to hitchhike, but their mother squashed that plan.) They quickly landed a gig at a bar called Moors, whose musical act had just been drafted. They arrived for their first show in carefully selected matching blouses.“Only later did we learn that the Moors was a gay and lesbian bar,” Carly Simon wrote in her 2015 memoir, “Boys in the Trees.” “What the mostly uncombed, ripped-jeans-and-motorcycle-jacketed audience made of these two sisters is lost to time. Lucy and I had taken our wardrobe at the Moors pretty seriously, and in return the audience probably thought we were twin milkmaids from Switzerland, or escapees from a nearby carnival.”They called themselves the Simon Sisters, even though, as Carly Simon wrote, “Lucy and I agreed that our stage name sounded schlocky and borderline embarrassing, plus neither of us wanted to be labeled — or dismissed — as just another novelty sister act.”In that book, Ms. Simon recalled the sisterly dynamic during that first foray into performing.“Anyone paying close attention would have seen how hard I, Carly, the younger sister, was trying to look and act like Lucy, the older sister,” she wrote. “I was now taller than Lucy, but emotionally speaking, Lucy was still the high-up one, the light, the beauty, the center of it all. Then as now, my sister was my grounding influence, my heroine, my pilot.”Soon they had a contract with a management company and were booked into the Bitter End, the Greenwich Village club that gave numerous future stars their start. An appearance on the musical variety television show “Hootenanny” in the spring of 1963 (along with the Chad Mitchell Trio and the Smothers Brothers) further boosted their profile. They appeared on the show again in early 1964.Some years earlier, Lucy Simon had composed a setting of the Eugene Field children’s poem “Wynken, Blynken, and Nod,” and the song became a staple of the Simon Sisters’ performances. Released as a single in 1964, titled “Winkin’, Blinkin’ and Nod,” it reached No. 73 on the Billboard chart. It also anchored one of the two albums they quickly recorded.The two sisters toured for a time, but after her marriage in 1967 to Dr. David Y. Levine, a psychiatrist, Lucy Simon pulled back from performing to focus on their two children. In 1975, she released a solo album, titled simply “Lucy Simon,” followed in 1977 by another, “Stolen Time.” But she found she had lost her zeal for performing.In the early 1980s, she and her husband produced two compilation albums featuring James Taylor, her sister Carly, Linda Ronstadt, Bette Midler and other stars singing children’s songs. The albums, “In Harmony: A Sesame Street Recording” and “In Harmony 2,” both won Grammy Awards for best children’s album.In the 1980s, Ms. Simon took a stab at musical theater, working on an effort to make a musical out of the “Little House on the Prairie” stories. That project never bore fruit, but a connection provided by her sister Joanna led her to one that did.Joanna Simon was for a time the arts correspondent for “The MacNeil/Lehrer NewsHour” on PBS, and in 1988 she interviewed the playwright Marsha Norman. She asked Ms. Norman what she was working on, and the playwright mentioned an adaptation of “The Secret Garden,” the Frances Hodgson Burnett children’s novel, and said that she and the producer Heidi Landesman were looking for a composer.Lucy, left, and Carly Simon singing in Shubert Alley along Broadway in 1982. Lucy Simon was later nominated for a Tony Award for best original score, for the hit musical “The Secret Garden.”Nancy Kaye/Associated PressLucy Simon proved to be a good fit for Ms. Norman’s lyrics. The show opened on Broadway in April 1991. Reviews were mixed — Frank Rich, in The Times, said that Ms. Simon’s music was “fetching when limning the deep feelings locked within the story’s family constellations” but not always successful — yet the show was a hit, giving 709 performances over almost two years. Ms. Simon earned a Tony nomination for best original score. (The award went to Cy Coleman, Betty Comden and Adolph Green for “The Will Rogers Follies.”)Ms. Simon reached Broadway again in 2015 as composer of the musical “Doctor Zhivago,” but the show lasted just 23 performances.That year, in the interview with The Times, she said that she thought music had the potential to be more emotionally powerful than other art forms, like dance or painting.“There’s something intangible and mysterious about music,” she said. “It can get you more; you can sob more. It’s got a stronger engine.”Lucy Elizabeth Simon was born on May 5, 1940, in Manhattan.“We all came out singing,’‘ she once said of herself and her sisters. “And we kept on singing. At dinner we wouldn’t just say, ‘Please pass the salt, thank you.’ We’d sing it. Sometimes in the style of Gershwin. Sometimes as a lieder.”Carly Simon wrote in her book that the pass-the-salt singing started as a way to help her — Carly — with a vexing stammer. Their mother had suggested that instead of speaking the phrase, Carly try singing it. With Joanna and Lucy joining in to encourage their sister, it worked.Lucy and Carly Simon during an interview with The New York Times in 2015 at Carly Simon’s home on Martha’s Vineyard, Mass.Ryan Conaty for The New York TimesLucy Simon’s greatest hit as a folk singer, the “Winkin’” song, had a self-help element to it. At 14, she was given a school assignment to memorize a poem, but dyslexia made it difficult. She found that she could memorize the Eugene Field poem by setting it to music. Her version was later recorded by numerous artists.Ms. Simon’s credits also included composing the music for a wild 1993 HBO movie, “The Positively True Adventures of the Alleged Texas Cheerleader Murdering Mom,” which won Emmy Awards for Holly Hunter and Beau Bridges.Ms. Simon’s brother, Peter, a photographer, died in 2018. In addition to her husband and her sister Carly, she is survived by two children, Julie Simon and James Levine, and four grandchildren.In 1985, Ms. Simon was in the hospital for surgery. She told a reporter that her two sisters had turned up to give her support.“When the stretcher came to take me to the operating room, we sang three-part harmony,” she said. “It lifted me.” More