Peter Mills Mattoon, 84, of Lafayette Hill, a longtime leader of the Philadelphia law firm Ballard Spahr, died Tuesday, March 29, at Jefferson University Hospital of injuries sustained in a fall.

Mr. Mattoon started in Ballard Spahr's relatively staid estates practice, but it wasn't long before he began to work in the more glamorous precincts of major-league sports, where he represented the 76ers and their owner at the time, philanthropist Eugene Dixon Jr.

His lawyering was so skillful that his colleagues at Ballard eventually elevated him to the role of firm chairman and he stayed in that leadership position for more than 16 years, until he stepped down in 1997.

Under Mr. Mattoon's leadership, Ballard Spahr greatly expanded its public-finance, business, and finance groups and established the firm as a force in litigation and real estate.

Never loud or flashy, he instituted a "one-firm Firm," a principal of institutional loyalty that became an enduring legacy, according to chair Mark Stewart.

His goal, he said in one speech, was "a civilized and successful firm."

Said Stewart, "His strong yet calming leadership, combined with the well-earned respect of his partners, took the firm to new heights and success."

Tall and dignified, Mr. Mattoon was a man of few words, almost none about himself. He projected the image of a strong, confident leader whose direction others would follow willingly.

Before he became chair, Mr. Mattoon served as Ballard's hiring partner, and he recruited a generation of lawyers, some of whom became firm leaders. His advice to young lawyers: Carefully observe the firm's partners, and follow their lead.

"Peter had that character, that presence," said Robert McQuiston, a retired partner. "He was just so sound, so solid, so deliberative, and he cared about the culture of the firm."

"He made us see the importance of working together," said partner John Langel, whom Mr. Mattoon hired, mentored in sports law, and eventually tapped to form the firm's highly regarded labor and employment practice.

In his legal practice, Mr. Mattoon was a trusted adviser to Marvin Wachman, president of Temple University from 1973 to 1983.

And when Dixon decided he wanted Julius Erving for the 76ers, it was Mr. Mattoon who helped close the deal that brought "Dr. J" to Philadelphia.

Mr. Mattoon's work for Dixon took on critical importance in the late 1970s and early 1980s when the two attended NBA owners' meetings together. Though Mr. Mattoon would rarely speak, he made an impression. David Stern, the league's general counsel who would become its commissioner, recalled that Mr. Mattoon was one of the most skillful lawyers he'd known.

Mr. Mattoon joined Ballard Spahr in 1959 after his graduation, cum laude, from Harvard Law School. He received his A.B. in 1953 from Dartmouth College, magna cum laude. In between, Mr. Mattoon served for three years as a Navy officer in the Pacific Fleet.

Born in Bryn Mawr, he graduated from the Episcopal Academy, whose board he later chaired.

Mr. Mattoon served on the boards of PNC Bank's Regional Advisory Board, Thomas Jefferson University, the 76ers, Provident National Bank, Widener University and the Widener University School of Law, and the Greater Philadelphia Chamber of Commerce.

He retired as a Ballard partner in 2001 and served as senior counsel through 2010.

Mr. Mattoon and his wife, Joan, to whom he was married for more than 60 years, lived on the Main Line and then in Lafayette Hill. At the time of his death, he was a resident of the Hill at Whitemarsh. The couple traveled extensively, and he continued to take classes at the University of Pennsylvania.

Besides his widow, Mr. Mattoon is survived by his daughter, Pamela Zisselman, of Annapolis, Md.; three sons, Stephen, of San Francisco; Peter, of Weston, Mass.; and Philip, of Minneapolis; and 10 grandchildren.

In lieu of flowers, donations may be made to the Educational Grant Committee for Part Time Employees at the Hill at Whitemarsh, 4000 Fox Hound Dr., Lafayette Hill, Pa. 19444

Services will be at 2 p.m. on Saturday, April 16, at the Presbyterian Church of Chestnut Hill, 8855 Germantown Ave., Philadelphia.

Interment will be private.

610-313-8232 @Kathy_Boccella