Emily W. Sunstein, 82, was a vocal leader of the reform movement that swept the Republican Party out of City Hall in 1951 after a reign of 67 years; head of the Southeastern chapter of the Americans for Democratic Action during the 1960s; and author of a seminal book about feminist and author Mary Shelley. She died Saturday at Thomas Jefferson University Hospital of complications of an autoimmune disease.

Mrs. Sunstein, a longtime resident of Chestnut Hill, moved to Rittenhouse Square three years ago.

"Emily was a major voice in the reform movement and, as head of the ADA in the 1960s, was a significant force in Philadelphia electoral politics," said Philadelphia lawyer Gregory M. Harvey, head of the ADA in the late 1970s.

Mrs. Sunstein, an early district organizer in the campaigns of Mayors Joseph S. Clark and Richardson Dilworth, described Philadelphia in the mid-1940s in a 1988 Inquirer story. She said that it was a city of corrupt institutions with a weak mayoral system and that Philadelphia's water was nationally notorious. "A glass of water was called a chlorine cocktail," Mrs. Sunstein said in 1988. "Raw sewage was being dumped in the Delaware [River]."

While chairwoman of the ADA, Mrs. Sunstein went head-to-head with Frank L. Rizzo. In 1961, Mrs. Sunstein called the appointment of Rizzo to police commissioner "a bad one." She said his record "indicates his preference for a heavy stick rather than a forceful word."

She was a sharp critic of Rizzo's handling of the riot that broke out in November 1967 between police and more than 3,000 African American students during a demonstration at the School Administration Building on the Parkway.

At least 20 people, including five policemen, were injured and 57 were arrested during the clash. Mrs. Sunstein said Rizzo's handling of the disturbance showed that "he didn't have the judgment necessary to handle potentially explosive situations."

In December 1967, she said the ADA was "more concerned for the welfare of the city than at any time since the organization was founded in 1947." She urged that "black power, white power and political power" be united to eliminate the "ominous polarization that is threatening Philadelphia."

In 1967, the ADA backed Republican Arlen Specter in the city's mayoral race. The ADA was sharply criticized by labor unions for supporting Specter.

At the urging of her mother, the former Emily Weisberg eschewed the image of a gracious Southern woman after graduating from high school in her native Dallas. A year before earning a bachelor's in art history in 1944 from Vassar College, she married stockbroker Leon Sunstein Jr. The couple moved to Elkins Park before raising three children in Wyncote.

She was on the state Commission for Human Relations from 1970 to 1974. "Mother was the head of the state Conference on Women's Economics Issues and the head of the Philadelphia YWCA in 1975. Then, she reached a crossroad in her life, and began to write books," daughter Kay Hymowitz said.

She and her husband built a sprawling modern cedar home with dramatic views of Fairmount Park in the mid-1970s. She filled the home with thousands of books and wrote A Different Face: The Life of Mary Wollstonecraft (Harper and Row, 1975). Wollstonecraft, mother of author Mary Shelley, was an early feminist in England.

In 1989, Mrs. Sunstein's Mary Shelley: Romance and Reality (Little, Brown and Co., 1989) was hailed by critics for scrapping the misconception of Shelley as a wan shadow of her husband. The biography was the first to use Shelley's recently published letters to describe her bouts of depression and said the cause of her death at 53 was a brain tumor.

Mrs. Sunstein won the prestigious Modern Language Association Prize for independent scholars in 1989, among other major literary awards.

"Mother became disillusioned by politics in the late 1970s," said her daughter. "She started to enjoy other passions such as writing, collecting art, entertaining and horticulture. She remained active in Jewish causes until she became ill in the mid-1990s."

"Emily was a magical entertainer," said Harvey. "At a party, she displayed a night-blooming cereus she grew in her greenhouse. It was propped up in the middle of the table. At about 11 p.m., it bloomed."

The cereus is a strange desert plant with an exquisitely scented flower that blooms for one midsummer's night each year, then closes with the morning sun.

In addition to her daughter Kay and husband, Mrs. Sunstein is survived by another daughter, Lauren; a son, Paul; six grandchildren; a brother; and a sister.

Services were Monday.

Donations may be made to the Rosenbach Museum, 2008 Delancey Place, Philadelphia 19103.