Among his charges: sociologists ignore racism and the role of the state in creating ghettos; they offer sanitized portraits of the urban poor instead of rigorous analysis of the reasons for their plight; and, worse, their work ends up providing unwitting legitimacy to regressive policies on race and poverty. He has also accused American scholars of cultural imperialism, of importing the peculiar national dynamics of race and racism to their studies of countries like Brazil, where the concepts make little sense.

As Mr. Wacquant put it last year in The American Journal of Sociology in a scathing review of three otherwise well-received urban ethnographies: ''U.S. sociology is now tied and party to the ongoing construction of the neoliberal state'' and its ''punitive management of the poor, on and off the street.''

This grim view of government conduct is the subject of his next book, ''Deadly Symbiosis,'' due out in the spring, which argues that American ghettos and prisons have become a single interconnected system for segregating and controlling the poor.

And while his writings have earned him acclaim -- his honors include a MacArthur Foundation ''genius award'' -- they have angered many of his colleagues.

''He's upset a lot of people,'' said William Julius Wilson, a university professor at Harvard who has made extensive studies of Chicago's ghettoes and been a central proponent of the view that racism is increasingly less significant in perpetuating urban poverty than are changes in the global economy and the local job market. He said he had read several chapters of ''Deadly Symbiosis'' and found much in them brilliant. ''However,'' he added, ''as with much of Loïc's work, I'm afraid that many readers will focus on the polemical attacks on the urban poverty literature instead of the powerful and substantive theoretical arguments he makes.''

Particularly galling, some scholars say, is that Mr. Wacquant has devoted much of his energy to reprimanding others while, at least until now, producing little fieldwork of his own. ''He doesn't go into these communities himself and often criticizes those who do,'' said Elijah Anderson, Charles and William Day distinguished professor of social sciences at the University of Pennsylvania and the author of ''Code of the Street: Decency, Violence, and the Moral Life of the Inner City'' (Norton, 1999), one of the ethnographies Mr. Wacquant has attacked. ''He'd like to see more militancy in the ghetto, but I'm trying to represent what's going on. If people in the ghetto community espouse a certain conventionality and conservatism, it's not for me to misrepresent.''

Certainly, ''Body & Soul,'' which Mr. Wacquant says is only the first installment of his work on boxing -- a second, more ambitious book, ''The Passion of the Pugilist,'' is under way -- bears little resemblance to Mr. Anderson's book. Mr. Wacquant calls his approach ''carnal sociology'' or ''ethnography by immersion.'' The goal, he says, is to convey his subjects' world by experiencing it firsthand -- in the case of his boxers, from the point of view of their sweaty, pummeled bodies. It's an ambition, he insists, that represents a radical departure from what passes as ethnography today.