Donald Bean, 103, a lawyer in Philadelphia for 64 years, died Saturday, Nov. 9, of pneumonia at his home in Society Hill.

In December 1945 Mr. Bean joined the law firm Wolf, Block, Schorr & Solis-Cohen, in which his father-in-law, George Schorr, was a partner. Mr. Schorr died a year later, but Mr. Bean rose quickly through the ranks, serving on the firm’s executive committee and as chairman of its real estate department for 12 years.

In 1987, after 42 years of practice, he reached the firm’s mandatory retirement age, but continued to do legal work until shortly before the firm disbanded in 2009, a victim of key partner defections and tight credit markets.

Mr. Bean took continuing legal education courses into his 90s, although he was retired. He was a member of the Pennsylvania Bar for 74 years.

He was a modest, unpretentious man. When asked at his 100th birthday party the secret of his longevity, he told family: “I always got plenty of sleep.”

The oldest child of Samuel Bean and Fanny Amster Bean, he was born in 1916 in Newark, N.J. His given name was Seymour Donald Bean, but he dropped the first name in his teens. He grew up in Newark and graduated from South Newark High School in 1934, Lafayette College in 1937, and Harvard Law School in 1940.

In 1941, he went to work for the federal government at what later became the War Production Board when it was established in January 1942 by an executive order of President Franklin D. Roosevelt. The board replaced two other government agencies.

In the fall of 1941, a friend introduced him to Fahnya Schorr, a Philadelphian and 1940 Smith College graduate. They were married in 1942.

Although Mr. Bean’s job in war production during World War II was deemed enough to earn him a deferment from active duty, he enlisted in the Naval Officers Training Program, and in April 1943 accepted a commission as an ensign in the Navy. He served throughout the remainder of the war as an officer in charge of Navy gun crews on two U.S. merchant ships. He was honorably discharged in 1945 with the rank of lieutenant.

He spent his free time on civic and charitable work, much of it for Jewish causes. From 1963 to 1967, as president of Congregation Rodeph Shalom, he oversaw the purchase of additional properties on the 600 block of North Broad Street, where the synagogue is located, enabling the congregation to expand its facilities a half-century later.

He was president of the Federation of Reform Synagogues and a board member of what is now the Union of Reform Judaism. He served on the union’s executive committee and its committee for rabbinical placement.

For 50 years, Mr. Bean served on the board of Jewish Family and Children’s Service of Greater Philadelphia, which honored him with two lifetime achievement awards.

He served on the Committee of Seventy in Philadelphia, and was active in the United Fund of Greater Philadelphia and Southern New Jersey. For many years, he was the oldest member of the Union League of Philadelphia.

Mr. Bean was an early convert to the culture of fitness. In 1957, when his wife gave birth to their third son, he took up jogging to increase his chances of seeing the boy reach adulthood. He continued jogging into his 70s, when he switched to walking, and he continued to walk daily until shortly before he died. At his death, his youngest son was 62.

“He had no fear of dissenting from received wisdom and no fear of following it when he thought it correct,” his family said. “He loved a good argument.”

His wife died in 2013. He is survived by sons Henry, George, and Donald Jr.; seven grandchildren; a great-granddaughter; and a sister.

Services were Sunday, Nov. 10, with interment in Mount Sinai Cemetery.