Richard J. Gelles, 73, of Philadelphia, a professor of social policy at the University of Pennsylvania whose pioneering research about family violence and child welfare helped shape government policy and social work practices nationwide, died June 26 of brain cancer at home.

“He never shied away from changing how things have always been done in order that we may all do them better,” said Amy Gutmann, president of the University of Pennsylvania. “In and of itself, such fearlessness is an excellent quality to have for any scholar, teacher, advocate, and leader.

“But, in Rich, that quality empowered the greatest of purposes: that of safeguarding the most vulnerable members of society.”

Dr. Gelles’ 1974 book, The Violent Home, was the first systematic investigation of family violence. It has been a building block for the academic field of social policy.

With the publication of The Book of David in 1996, Dr. Gelles helped raise awareness of the tragic, sometimes unintended consequences of trying to reunite children in foster care with their biological families, whatever the domestic history.

The book, which advocated that children did best when they were positioned in the child welfare system to find permanent adoptive homes, helped lead to the passage of the Adoption and Safe Families Act of 1997.

The act included a provision known as the 15/22 rule. If a child had been in foster care for 15 of the previous 22 months, states were required to terminate the biological parents’ rights so that the child could be put up for adoption. As a result, more foster children found adoptive homes.

He also changed the lives of individual children who had been abused by the foster care system by bringing the abuse to the attention of the news media and the legal system, his family said.

Born in Newton, Mass., Dr. Gelles graduated from Newton South High School and earned a bachelor’s degree from Bates College, a master’s degree in sociology from the University of Rochester, and a doctorate in sociology from the University of New Hampshire.

He came to Penn in 1998 from the University of Rhode Island, where he had taught and conducted research on domestic violence since 1973.

In 2001, he became interim dean of what was then Penn’s School of Social Work. He was named dean in 2003. When then-Penn president Judith Rodin said she was considering closing the school, he told her, “It can be made viable with some very simple steps,” the Daily Pennsylvanian reported in March 2014.

Dr. Gelles changed the name to the School of Social Policy and Practice, expanded the offerings to include a master’s degree in nonprofit leadership and social policy, and raised $33.6 million for the school between 2005 and 2012.

“The school is in a much better shape today than when he took it over,” Ram Cnaan, a professor at the graduate school, told the newspaper in 2014, when Dr. Gelles stepped down as dean. “Academically, student-wise, budget-wise, on all fronts, much better.”

Dr. Gelles was a sociologist at Penn from 1998 to 2019 and occupied the Joanne and Raymond Welsh Chair of Child Welfare and Family Violence. He was faculty director of the school’s Field Center for Children’s Policy, Practice & Research.

He trained and consulted with federal, state and municipal child protective agencies and served as an expert witness on child welfare issues in courts across the country. He advocated for his views on TV and public radio.

He was a consultant to the Army on domestic violence issues. His study showed that the highest rate of domestic violence was not in those deployed for combat or special assignments abroad, but rather in those who stayed home and restocked supplies for foreign missions.

A former college baseball player, he was a diehard fan of both the Boston Red Sox and the Phillies.

In 1971, he married Judy Gelles, an artist, photographer, and filmmaker. They raised two sons in Rhode Island before moving to Philadelphia. She died March 14.

Dr. Gelles is survived by sons David P. Gelles and Jason Gelles, and three grandchildren.

Services were June 28.

Memorial donations may be made to Camp Tevya through https://secure.qgiv.com/for/tevya or to Society Hill Synagogue through https://www.societyhillsynagogue.org/donation-form/.