Stephen Birmingham, author of “Our Crowd” and other books chronicling wealth and celebrity in America. (The Hotchkiss School)

Stephen Birmingham, an author whose frothy books of social history, such as “Our Crowd” and “The Rest of Us,” were best-selling sagas of American aristocracy, often viewed through the lens of ethnic minorities, died Nov. 15 at his home in New York City. He was 86.

The cause was lung cancer, said his longtime partner, Edward Lahniers.

Mr. Birmingham began his literary career as a novelist, dissecting the manners of the prep-school class, before turning his attention to what he called New York’s “other society” — the German-Jewish dynasties that had dominated Manhattan’s banking and brokerage circles for a century.

“Our Crowd: The Great Jewish Families of New York” became a No. 1 bestseller in 1967, was made into a musical and launched a literary franchise for Mr. Birmingham as a chronicler of wealth and celebrity.

He wrote other nonfiction accounts of life among the upper echelons of Jewish, Irish, African American and old-line Anglo-Saxon society. He also published biographies of first lady Jacqueline Kennedy Onassis and socialite Wallis Warfield Simpson, as well as several novels.

He chose his subjects for a simple reason: “I think rich people are more interesting than poor people,” he quipped in 1984. “You know, sometimes I feel rather sorry for the rich, because I’m practically the only one who’s paying any attention to them.”

“Our Crowd,” which focused on the little-known world of German Jewish families in New York, proved to be something a landmark and was hailed in Newsweek as a “sprightly, delightfully gossipy social history.”

Mr. Birmingham, who was of Irish and British ancestry and was not Jewish, had attended the exclusive Hotchkiss prep school in Connecticut with descendants of several families who controlled financial empires established in the 19th century.

He became fascinated with the idea of exploring the social and commercial lives of the Lehmans, Warburgs, Guggenheims, Schiffs and other families he called, correctly or not, “the closest thing to aristocracy that the city, and perhaps the country, had seen.”

He followed the same breezy formula in “The Grandees: America’s Sephardic Elite” (1971) and “The Rest of Us: The Rise of America’s Eastern European Jews” (1984), which looked at the rise of such 20th-century figures as movie mogul Samuel Goldwyn and gangster Meyer Lansky.

His best sources, Mr. Birmingham said, were elderly women who loved to talk about their friends and relatives.

“If you get an old lady with all her marbles and lots of time on her hands to pull out family scrapbooks, show the locks of baby hair, share all the memories,” he told the Chicago Tribune in 1987, “it can be quite wonderful.”

Mr. Birmingham’s books flew off the shelves and made him something of a celebrity in his own right, with appearances on Johnny Carson’s and Merv Griffin’s talk shows.

When he turned to other social groups in “Real Lace: America’s Irish Rich” (1973) and “Certain People: America’s Black Elite” (1977), Mr. Birmingham began to lose his footing.

“Certain People,” in particular, met with hostile reviews as critics questioned Mr. Birmingham’s conclusions and the premise of a white man writing about the inner workings of black society.

“ ‘Certain People’ is so flawed that it is hard to decide where to find fault first,” critic Le Anne Schreiber wrote in Time magazine in 1977, saying Mr. Birmingham “remains insensitive to the tragic involutions of identity that make the black elite very different from — and much more vulnerable than — its white counterpart.”

An undaunted Mr. Birmingham continued to churn out bestsellers, even when he could not get close to his subjects. He sought for years without success to gain access to the private world of Jackie Onassis. In the end, he forged ahead with his 1978 biography without her consent.

“Steadfastly — politely, but firmly — she refused to give interviews,” he wrote. “Even close friends in the media have been unable to change her mind. And so — serene, smiling, aloof, mysterious, enigmatic and unapproachable — surrounded and protected by a small coterie of friends, Jacqueline Onassis remains sphinxlike, Garbolike, our most tantalizing, most exasperating celebrity.”

Stephen Gardner Birmingham was born May 28, 1929, in Hartford, Conn. His father was a lawyer.

Mr. Birmingham graduated in 1950 from Williams College in Williamstown, Mass., where he was an English major. He served in the Army during the Korean War, then worked in advertising in New York. He reportedly coined the slogan for Ladies’ Home Journal magazine: “Never underestimate the power of a woman.”

In his spare time, he began writing for magazines in the 1950s and published his first novel in 1958. His mentor was the Pulitzer Prize-winning novelist John P. Marquand, about whom Mr. Birmingham published a biography in 1972.

The success of “Our Crowd” allowed Mr. Birmingham to pursue writing full time. He moved in 1973 to Cincinnati, where he taught writing at the University of Cincinnati for several years. He continued to live in Cincinnati, with frequent visits to his apartment in New York, until his death.

His marriage to Jane Tillson ended in divorce. Survivors include his partner of 42 years, Edward Lahniers of Cincinnati; three children from his marriage, Carey Birmingham and Harriet Birmingham, both of San Antonio, and Mark Birmingham of Fort Collins, Colo.; a sister; and a granddaughter.

Mr. Birmingham wrote more than 25 volumes in all. His final book, the novel “The Wrong Kind of Money,” appeared in 1997. He was working on a memoir at the time of his death, and many of his books are scheduled to be republished in electronic and paperback editions in the coming months.

“I’ve never wanted to write a scholarly tome bristling with footnotes, because I don’t like to read that sort of book for pleasure,” he told the Miami Herald in 1984. “I feel I’m in show business. I’m an entertainer who first wants to entertain myself. What’s wrong with that?”