It took a while, but 81-year-old Robert Rothstein Jr. of Chevy Chase finally graduated from high school last month.

Rothstein became the oldest person ever to earn a high school diploma from a Montgomery County public school when he passed a proficiency exam given in December, school officials said. The Montgomery County Board of Education does not plan to let the feat go unnoticed. Rothstein will be honored at the school board's meeting next Tuesday.

What is it that motivates an 81-year-old man to get his high school diploma?

"I told my son last April that if he completed his PhD I would go after my high school diploma," the New York native said. "When I got back from visiting him in Hawaii I immediately looked into taking these exams . . . . Before that I had never really worried about finishing high school."

Several other milestones were placed late in Rothstein's life: He married when he was 46 years old and then had three children. Just last year he was bar mitzvahed at Temple Sinai in Chevy Chase.

"When the rabbi heard I was going to be 80, he said, 'You're going to go for this solo.' So they had a special ceremony for me," said Rothstein, adding that being bar mitzvahed was far more of a thrill than earning his high school diploma.

The octogenarian is well-known at school board headquarters.

"I think it's marvelous," said board member Blair Ewing of the new degree. Mr. Rothstein has clearly persevered and I admire him for that."

Rothstein has never had much time to worry about completing high school. He grew up on New York City's East Side and dropped out of school when he was 14 to help support his mother, a Russian immigrant who worked in a sweatshop turning men's ties inside out.

"My father died when I was 3 and my mother had to put my two older brothers in the Brookland Hebrew Orphans Home because she couldn't afford to support them. We were only allowed to visit them every three months for just a few hours," he recalled.

Rothstein says his mother was broken-hearted over the arrangement, and he remembers her standing at the fence that surrounded the orphanage watching her sons play.

By the time he dropped out of high school, Rothstein's brothers had jobs and the entire family lived with an uncle in a small, two-bedroom apartment that rented for $14 a month.

Earning only $7 a week and helping to support his family, Rothstein managed to save $8,000 by the time he was 22, when he formed a men's clothing company with a friend who invested $2,000. The firm was soon grossing more than $1 million a year, he said. Rothstein sold it in 1935.

He traveled around the world for a year and then moved to Washington to become a dental technician apprentice for his uncle, who owned Rothstein Dental Laboratories.

"In 1941, everyone was in uniform and they all had dates. So at age 40 I enlisted in the Army and got stationed at Camp Lee, Va.," Rothstein recalled.

When he got out of the Army 2 1/2 years later he again worked for his uncle and was married. He and his wife, Sylvia, now have one grandchild, with another on the way.

"Because I never finished high school I insisted that all my children go to good colleges," Rothstein said.

His oldest daughter, Francis Rothstein Wolk, 35, of Chevy Chase, has a bachelor's degree from Brown University.

Another daughter, Susan Rothstein Koeptel, 33, who lives in San Francisco, has a BA from Tufts University and an MBA from Stanford University. His son, Joseph, 30, teaches computer music at the University of Hawaii; he has a BA from Bennington College and a master's degree from the State University of New York at Buffalo and is completing his PhD.

Rothstein and his wife swim and play golf, he said. Last summer, while visiting his daughter in San Francisco, he flew in a glider for the first time.