Manford had been experiencing declining health for some time, according to her daughter, Suzanne Swan.
PFLAG's executive director, Jody M. Huckaby, said the world had lost a pioneer with Manford's death.
"Jeanne was one of the fiercest fighters in the battle for acceptance and equality for lesbian, gay, bisexual and transgender people," Huckaby said. "It is truly humbling to imagine in 1972 — just 40 years ago — a simple schoolteacher started this movement of family and ally support, without benefit of any of the technology that today makes a grassroots movement so easy to organize. No Internet. No cell phones. Just a deep love for her son and a sign reading 'Parents of Gays: Unite in Support for Our Children.'"
One of Manford's sons, the late Morty Manford, was gay. He was beaten during a Gay Activists Alliance demonstration in April 1972, and police failed to intervene. She wrote a letter to the New York Post, published April 29, 1972, in which she stated, "I have a homosexual son, and I love him." Her letter sparked a groundswell of response, and less than two months later, she joined her son at the Christopher Street Liberation Day Parade. Her participation and the affirmations she received from others eventually led to the beginning of PFLAG.
The first meeting, with 20 people, was at a Metropolitan Community Church on March 11, 1973. PFLAG now has 350 official chapters across the U.S. and 200,000 members.
In addition to her daughter, Manford is survived by her son-in-law, Richard Swan, her granddaughter, Avril Swan, and Avril's husband, Stuart Streepy, and her great-granddaughters, Clara, Grace, and Jules. Manford and her late husband, Jules, also had two sons: Charles, who died in 1966, and Morty, who died in 1992.
"She is known to thousands of people as the mother of the straight ally movement," Suzanne Swan said, "but to me, she was my mother."