"Like most writers on poverty in the late 1980s, I did not realize how hegemonic the conservative story of welfare and poverty had become, and how far to the right American social politics would shift, even under Democratic administrations," he wrote.
"Nor did [I] grasp that massive economic inequality accompanied by declining real wages, the erosion of private as well as public employee benefits, and the rise of . . . the 'gig economy' would define a new social structure of insecurity," he wrote.
The poor were defined less by what is said about them, he posited, than by how they are treated in legislation and administrative action. Once he logged that treatment, he began to see that certain forces were preventing a rise out of poverty and that the newest members of the underclass were undocumented immigrants.
He also saw immigrants as "positive and productive, and as transforming American cities in ways we never foresaw," his family said in a tribute.
Dr. Katz was a codirector of Penn's urban studies program from 1983 until 1996.
"He, more than any individual, [was] responsible for the current contours of the undergraduate program," wrote codirectors Mark Stern and Elaine Simon. "Early in his tenure, he restructured the curriculum, balancing multidisciplinary coursework with a core of shared experiences."
Dr. Katz shaped the senior seminar as "the major's capstone," the two said in a post on the program's website. He encouraged students to approach him at lunch, was a powerful teacher, and made himself available as a mentor.
He introduced the annual urban studies lecture, which brings a leading urban scholar to the Penn campus.
A busy speaker and prolific writer, he wrote, or contributed to, 17 books. In his last major book - Why Don't American Cities Burn? - he challenged progressives to develop a narrative of American cities that balanced skepticism with hope.
Educated at Harvard, Dr. Katz was at various times a Guggenheim Fellow and a resident fellow at institutes including the Russell Sage Foundation and the Woodrow Wilson International Center for Scholars.
Pennsylvania Gov. Robert P. Casey appointed him in 1992 to the Task Force to Reduce Welfare Dependency.
In 1999, he received a Senior Scholar Award, marking a lifetime of achievement from the Spencer Foundation. He was thrilled at being inducted into the American Philosophical Society, his family said.
Born in Wilmington, he graduated from Marblehead (Mass.) High School. He and his wife, Edda Gering Katz, lived in Toronto, where Dr. Katz taught, before moving to Philadelphia in 1978.
Surviving, besides his wife, are a son, Paul; daughters Rebecca and Sarah; seven grandchildren; and a great-grandchild.
A graveside service was set for 1 p.m. Wednesday, Aug. 27, at Evergreen Cemetery, Rangeley, Maine. He had summered in nearby Oquossoc since 1979. Plans for a memorial at Penn were pending.
Contributions may be made to HIAS Pennsylvania via http://hiaspa.org/, Bread & Roses community fund via http://breadrosesfund.org/, or the Abramson Cancer Center of the University of Pennsylvania via www.penncancer.org/patients/giving/.