Priscilla L. Buckley, a journalist who was the longtime managing editor of National Review, the conservative magazine founded by her brother William F. Buckley Jr., died on Sunday at her home in Sharon, Conn. She was 90.

Her death, at Great Elm, the 30-room Georgian mansion in which Miss Buckley and her siblings were reared, was of kidney failure, said her nephew Christopher Buckley, a writer and Mr. Buckley's son. Miss Buckley had lived for many years in one of the several condominiums into which Great Elm was partitioned in the 1980s.

Miss Buckley, who was associated with National Review for more than four decades, was its managing editor from 1959 to 1985. In that role, she oversaw the day-to-day operations of the magazine, riding herd — by all accounts without raising her voice so much as a decibel — on a staff of occasionally bibulous, sometimes fractious and constitutionally dilatory writers.

Reviewing the second volume of Miss Buckley's memoirs in 2005, National Review itself wrote that she had "played a quiet but critical role in molding the modern conservative movement." As a result of her sustained velvet-gloved sway there, the magazine was long known among its denizens as Miss Buckley's Finishing School for Young Ladies and Gentlemen of Conservative Persuasion.

She also helped shape the magazine's editorial profile, as when, in June 1968, after receiving word of Robert F. Kennedy's assassination, she pulled a highly critical cover story about him shortly before press time.

The third of 10 children of William Frank Buckley, an oil executive, and the former Aloïse Steiner, Priscilla Langford Buckley, familiarly known as Pitts, was born in New York City on Oct. 17, 1921. She earned a bachelor's degree in history from Smith College in 1943. The next year she joined United Press, as the news service was then known, writing copy for the radio news desk from its New York office.

After a stint with the Central Intelligence Agency, where she prepared reports on overseas operations, she rejoined United Press as a reporter in its Paris bureau. In 1956, the year after National Review was founded, she returned to the United States to join the magazine at her brother's request. When National Review's original managing editor, Suzanne La Follette, retired, Miss Buckley was recommended for the post by Whittaker Chambers, a Communist-turned-conservative who was a member of the editorial board.

After stepping down as managing editor, Miss Buckley was a senior editor at the magazine until her formal retirement in 1999.

Miss Buckley, who never married, is survived by two brothers — James L. Buckley, a retired federal judge who, as a member of the Conservative Party, represented New York in the United States Senate from 1971 to 1977, and F. Reid Buckley — and a sister, Carol Buckley. William F. Buckley Jr., the sixth of the Buckley siblings, died in 2008.

Miss Buckley's books include Volume 1 of her memoirs, "String of Pearls: On the News Beat in New York and Paris," published in 2001. After Volume 2 was published four years later, she was often asked why she chose its more than slightly counterintuitive title, "Living It Up With National Review."

The title was meant, she replied, as a kind of light counterweight to public perception.

"National Review will go down in history as a very serious, solemn, ideologically driven magazine, and that was not the magazine I worked for," Miss Buckley told The Litchfield County Times of Connecticut in 2005. "My magazine was a lot of fun." (--obituary, Margalit Fox, The New York Times, New York, NY, 26 March 2012)