His daughter, Sarah Glazer Khedouri, confirmed his death.

Over the course of more than half a century, Glazer threw himself into the middle of heated debates over contentious issues such as race, ethnicity, immigration and education, contributing to a range of professional journals and popular magazines, and writing or editing more than a dozen books. He once said that he often held positions no different from many others’, but that he was the one who would go to meetings and speak up.

Early in his career, he was the co-author of two seminal works on American society, “The Lonely Crowd,” with David Riesman and Reuel Denney in 1950, and “Beyond the Melting Pot,” with Daniel Patrick Moynihan in 1963. Later volumes included “We Are All Multiculturalists Now” in 1997 and “From a Cause to a Style: Modernist Architecture’s Encounter with the American City” in 2007.

He also worked as an editor at the magazines Commentary and The Public Interest, and Doubleday Anchor Books. He served on presidential task forces on urban affairs and education, and held teaching positions at Bennington College, Smith College and the University of California, Berkeley. At the time of his death, he was a professor emeritus of sociology and education at Harvard University.

The child of Jewish immigrants, he was born on Feb. 25, 1923, in New York City and spent his early years in East Harlem.

His father, Louis Glazer, was a garment worker, and his mother, Tilly Glazer, was a homemaker. He was the youngest of seven children, and when he was 10, the family, which was crammed into a four-room apartment, moved to the wider spaces of the East Bronx.

Glazer’s interest in urban affairs stemmed directly from personal experience, and his early upbringing had a permanent impact on his later ideas. His East Harlem tenement block had no trees or green strips. Brick and concrete dominated, along with the iron structures of elevated trains. It was, Glazer once said, a “bad place to live.”

Only a few blocks away was Central Park, where a young boy could lose himself in the meadows and woodlands, enjoying a respite from the city’s constant noise and grime. For Glazer, the park was a “wonder” of childhood, and in years to come, when some urban planners challenged Frederick Law Olmsted’s vision of a pastoral retreat within a crowded city, Glazer spoke out in Olmsted’s defense and in favor of green spaces like his beloved Central Park.

Glazer arrived at City College in 1940, near the end of the Great Depression and at a time when the all-male, predominantly Jewish student body was largely divided into antagonistic leftist factions — Stalinist, Trotskyist, Socialist. Having inherited a Socialist, anti-Communist perspective from his trade-unionist father, Glazer lined up against the Stalinists, joined a radical Zionist organization and edited its newspaper.

After graduation in 1944, he got a job at The Contemporary Jewish Record, soon to become Commentary. Glazer said that he came out of a “very narrow world,” describing his life in the late 1940s and early 1950s as leaving “the womb.”

In the presidential election of 1948, he voted for Socialist Norman Thomas, not Democrat Harry Truman, but said, “I felt silly about it.”

Two groups of thinkers that have had a lasting impact on American culture had a lasting impact on Glazer as well. The first was the New York Intellectuals, the collection of writers gathered around Partisan Review and later The New York Review of Books, who combined leftist politics with modernist aesthetics. Early influences on his ideas were Partisan Review writers Dwight Macdonald and Hannah Arendt; another contributor to the magazine, art critic Clement Greenberg, helped get him his first job.

While he was at Commentary, his circle of acquaintances began to widen. Writers like James Baldwin and Irving Howe would drop by the office, and at Greenwich Village parties he met prominent intellectuals like Lionel Trilling and Partisan Review editors Philip Rahv and William Phillips. These were people, Glazer said, who seemed to be “working at the forefront of knowledge,” with their understanding of Marx, Freud and Modernist developments in the arts.

“There was an awful lot of talk,” Glazer once said, but he always felt something of an outsider, a “junior member” at these get-togethers, “more like a hanger-on” than a full participant.

Glazer’s turn to neoconservatism followed an almost paradigmatic path.

Throughout the ‘50s, and even after he went to work for the Kennedy administration’s Housing and Home Finance Agency in 1962-63, he continued to consider himself a radical. But if, as his longtime friend Irving Kristol put it, a neoconservative is a liberal who has been mugged by reality, then Glazer got hit over the head after taking a teaching post at Berkeley in 1963, just as the student rebellions of the 1960s were erupting.

Opposed to the growing American involvement in Vietnam and supportive of social policies designed to help the poor, Glazer initially sympathized with the student protesters. But as they grew more extreme and anti-American — “nihilistic” was Glazer’s word — he turned away from them and his own leftist past as well. He moved toward what he saw as a hard-won pragmatism but what others saw as a reactive conservatism.

In 1965, Glazer became one of the original contributors to The Public Interest, founded by Kristol and another friend, Daniel Bell. The magazine was a policy journal grounded in the concreteness of empirical evidence and asked hard questions about Great Society programs.

It became the most intellectually formidable of the neoconservative publications in the last decades of the 20th Century, and one that Glazer edited with Kristol from 1973 until its demise in 2005.

During the battles of the 1970s over busing and affirmative action, he published “Affirmative Discrimination” in 1975, a landmark statement for neoconservatives and others opposed to government-enforced racial balancing. Glazer was prominently featured in one of the earliest studies of the group, Peter Steinfels’ “The Neoconservatives: The Men Who Are Changing America’s Politics” in 1979.

Glazer is survived by his wife, Sulochana Glazer, and his three daughters from his first marriage: Sarah Glazer Khedouri, Elizabeth Glazer and Sophie Glazer. He is also survived by seven grandchildren and two great-grandchildren.

Glazer was never an entirely reliable neoconservative. He wasn’t comfortable with the label, and on foreign policy continued to describe himself as “somewhat left.” If he opposed policies like affirmative action, it was not, like more traditional conservatives, out of an antipathy to government itself, but out of a skepticism about what public programs could accomplish.

One of his books was titled “The Limits of Social Policy,” published in 1988.

“On most areas of public policy,” he said, “I consider myself pragmatic, rather than a man of the left or a man of the right.”

As a social scientist, he valued hard facts over good intentions. At the same time, he was modest about what the facts could show. A reader of his work was always coming upon phrases like “I am not sure” and “We do not have the knowledge” and “I do not know.”

This meant that the nonideological Glazer could change his mind. In his writings on architecture and city planning, for example, he went from an early enthusiasm for modernism to a “growing disenchantment.”

“In the end,” he said, “the defense of a radical modernism became the work of an elite that the ordinary person could not understand.”

During the 1990s he decided he had been wrong about the course of integration as set out in “Affirmative Discrimination” — that he had been too complacent about racial progress in America.

And once he concluded that some kind of multiculturalism was necessary for public education, he bowed to what he saw as the inevitable: “Even the most balanced and professional effort to define a curriculum for students in American schools today will place a heavy emphasis on multiplicity and diversity, race and ethnicity.”

In Glazer’s case, it seemed, a multiculturalist was a neoconservative who had been mugged by reality. Former allies were not pleased. One historian of neoconservatism, writing in 2005, spoke of Glazer’s “defection” from the movement.

Yet there was an underlying consistency to Glazer’s political and policy shifts. He had become a pessimist about the effectiveness of government programs and therefore a critic of much social policy. “I know what I’m against,” he said.

But he said this more with sorrow than satisfaction. For if his skepticism compelled him to leave most of his radical past behind, he never fully abandoned his youthful concerns about social justice.

Late in life he described himself as a “meliorist,” and in a statement that can stand as his political testament, he declared: “I think you must keep on trying, even if you haven’t had great success. I think everything helps a little.”