Carleton S. Coon Jr., a career Foreign Service officer who balanced professional and family diplomacy as ambassador to Nepal while his wife served as ambassador to nearby Bangladesh, died Dec. 3 at a hospital in Warrenton, Va. He was 91.

The cause was biliary sepsis, said his wife, Jane Abell Coon, who also was a career Foreign Service officer.

For three years beginning in 1981, Mr. Coon and his wife served respectively in Kathmandu and Dhaka. “Can a good marriage withstand having two ambassadors in the family?” the New York Times facetiously asked in a 1981 story on the Coons’ appointments.

“Yes, it thrived,” said Mr. Coon’s daughter Ellen Coon. “They celebrated their 50th wedding anniversary last year.”

In deference to State Department traditions for female Foreign Service officers, Jane Abell Coon retired after 17 years in the government when she married Mr. Coon, a widowed father of six, in 1968. It was a tradition that did not apply to male Foreign Service officers.

However, the protocol already had been breached at least once. In 1967, Carol Laise, then the ambassador to Nepal, married Ellsworth Bunker, an ambassador at large who later became ambassador to South Vietnam. At their wedding in Nepal, they received a congratulatory telegram from President Lyndon B. Johnson, which would have made it exceedingly difficult for a State Department bureaucrat to have insisted that Carol Laise Bunker leave the Foreign Service.

For nine years, Jane Coon helped raise her stepchildren. The experience, she said, “had its moments.” Resuming her professional life in 1976 after the State Department became less hostile to the idea of dual diplomatic spouses, she was a deputy assistant secretary before her appointment as ambassador to Bangladesh.

As ambassadors, the Coons were only 90 minutes apart by airplane. “That’s better than you can do between New York and Washington,” Mrs. Coon told People magazine at the time.

They visited each other regularly. Children came over for Christmas. There were exploratory family treks in the Nepalese mountains.

“The way we live these days is an abnormal way to run a marriage,” Mr. Coon told People, “but now at least when I see her, I see her . . . After all, it’s nice to be an ambassador after 30 years of understudying the role.”

Carlton Coon retired from the Foreign Service in 1985, and his wife retired the next year.

Carleton Stevens Coon Jr. was born in Paris on April 27, 1927. His father, a celebrated anthropologist, was on an expedition in Morocco at the time. The younger Coon graduated from the private Phillips Academy in Andover, Mass., served in the Army at the end of World War II and graduated from Harvard in 1949.

After joining Foreign Service that same year, he went on to serve in Germany, Syria, India, Iran and Morocco. As director of North African affairs, he had oversight of U.S. relations with the Libyan strongman Moammar Gaddafi.

His first wife, Janet Wulsin, died in 1967. Their son William P. Coon died in 1996.

In addition to Jane Coon of Woodville, Va., survivors include his five children, Howard W. Coon of Castleton, Va., Katharine A. Coon of Takoma Park, Md., Ellen J. Coon of New York, and Elizabeth Gaskill and Richard G. Coon, both of Chico, Calif.; 13 grandchildren, and 12 great-grandchildren.