J. Willard O’Brien, 90, credited with leading Villanova University’s law school into a new generation of growth and inclusiveness as its second dean, died Dec. 22 of heart failure at his home in Wayne.

Mr. O’Brien, who grew up playing stickball on the streets of the Bronx, was a demanding torts professor and served as dean from 1972 to 1983. He hired more professors, driving down the student-to-faculty ratio, increased their pay, and made a priority of hiring women and people of color for teaching positions, according to a history of the law school.

Only 42 years old when his peers unanimously elected him dean. Mr. O’Brien was a calm and self-possessed man, if a bit formal, and earned respect for an ability to listen to people and navigate academic politics. He was known as “Willard” or “Bill.”

“His days on earth have ended, but his legacy and spirit remain in our community,” said Mark Alexander, dean of what is now known as the Charles Widger School of Law.

Mr. O’Brien earned his bachelor’s degree at Fordham University in 1952. He served as an intelligence officer in the Air Force and received his law degree in 1957 from Fordham Law School, where he was editor-in-chief of the law review.

He worked for a Wall Street firm before joining Syracuse University’s law faculty. In 1965, Villanova recruited him. He became legendary for his style and precise Socratic questions.

“I never saw him in the building when he wasn’t wearing a three-piece suit with a gold pocket watch and a shirt with French cuffs,” said Doris Brogan, a professor at Villanova’s law school who was Mr. O’Brien’s student in 1978 and later, colleague.

Mr. O’Brien met his wife, Peggy, in 1979 when he was 49. His family said he called her “my love” and introduced her to others as “my bride” for the rest of his life.

“He was sweet to my mother — never sat at the dinner table until she sat, and always kissed her before they ate,” said his stepdaughter, Stephanie Gruner Buckley, of London. He was a “classy man from a different age,” she said.

“He taught me and my brother that decency matters,” she said. “I can’t imagine a better role model, a better stepdad.”

Most important, she said, her father — who grew up poor and paid his way through school by working at a restaurant and installing car seats — was determined to help people from disadvantaged backgrounds “prosper equally” in the profession.

His wife was a broker selling condominium timeshares at the Tennis Club of Palm Beach in Florida when they met. Mr. O’Brien was an avid tennis player who stopped in the office at the end of a long day to inquire about buying a condo.

They didn’t see each other until a year later when he came back for vacation.

“I’d pick up the phone and then hang up before I dialed it. I said to myself, ‘He doesn’t want to talk to me. He’s the dean of a law school,’“ Peggy O’Brien said. “He was doing the same thing — ‘Well, she probably has three or four boyfriends.’”

The next year, she invited him over for a glass of wine. They stood on her balcony for two hours talking. Three months later, in June 1980, they married.

Brogan said clarity and precision mattered to Mr. O’Brien — something she learned in her first year of law school.

One day, a student was reciting the facts of a case, in which a woman asked a store clerk where the frozen peas were. The young man said she spoke to “some guy.”

“I remember Bill taking off his glasses and staring down at the kid who didn’t realize it and kept talking,” Brogan said. “He said ‘Guy? Some guy?’ We were terrified.” The student stammered and corrected himself.

“He was shaping us into lawyers,” she said. “But Bill wasn’t mean or vicious. He gave you the opportunity to go back and amend.”

In 1983, Mr. O’Brien stepped down as dean, continued to teach and became director of a center studying the law morality.

In addition to his wife and stepdaughter, Mr. O’Brien is survived by his stepson, Mitchell Gruner; a brother and sister; and several grandchildren.

A memorial service is being planned for the spring. Contributions may be made to the David F. and Constance B. Girard-diCarlo Center for Ethics, Integrity and Compliance, 299 North Spring Mill Road, Villanova, Pa. 19085 or a charity of the giver’s choice.