It has been something of a surprise, given that the problems of the American inner city have become a less urgent public obsession in recent years, to discover an emerging renaissance in the field of ghetto sociology. In popular culture, the pioneer in this arena has been David Simon, the creator of the HBO series The Wire, who has treated his subjects with a rare degree of intimacy and sophistication. In academia, the crucial figure has been the Columbia sociologist Sudhir Venkatesh, whose immersion studies of the underground economy have done as much as any investigator to discover how the mechanisms of the ghetto really work.

Venkatesh has just written a new memoir of his research, Gang Leader for a Day: A Rogue Sociologist Takes to the Streets. In 1989, Venkatesh was a graduate student in sociology at the University of Chicago, a suburban kid from California with deadhead hair, professor parents, and a generally benign, hippie-inflected take on things. At Chicago, he ended up in the orbit of William Julius Wilson, the famed black scholar of the ghetto. Wilson was contemplating a project that would, initially through a set of questionnaires given to young black youth, aim to distinguish what effect the ghetto had in limiting opportunity, beyond the normal impairments that come with poverty in the United States. In what ways, that is, was the experience of the ghetto unique?

In an episode that sounds suspiciously like grad student hazing, Venkatesh was dispatched to ask survey questions of young black men living in a Chicago housing project, the Robert Taylor Homes. He asks, for instance, “How does it feel to be black and poor? Very bad, somewhat bad, neither bad nor good, somewhat good, very good?” He gets laughed at. “Fuck you, you got to be fucking kidding me,” one kid tells him. He is briefly suspected of being a Mexican gang member, and then merely mocked vigorously. But eventually he is taken under the wing of a drug dealer, whom Venkatesh calls J.T.

The dealer runs an area of the housing project for a citywide gang called the Black Kings, and over the course of five years he gives Venkatesh full access to his operation. J.T. permits the sociologist a close and privileged view of ghetto life that few other academics have ever managed. It is an astonishing bit of luck. Venkatesh starts to hang out at the Taylor Homes every day, and his intimate access to the gang leader becomes the source of his research—and, ultimately, his fame. (Venkatesh and J.T. were both featured in the 2005 best seller Freakonomics, and in 2006 Venkatesh published Off the Books: The Underground Economy of the Urban Poor, based on research from his time at the project.) On the back flap of Gang Leader for a Day, the author Barbara Ehrenreich calls J.T. “one of the greatest characters to emerge from something that could be called sociological research.”

In the project, Venkatesh finds men and women who easily flit back and forth between the legal and illegal economies (depending, usually, on which pays more at any given moment). Drug dealers aspire to buy small businesses, and their subordinates move between legitimate jobs and the hustle of drug dealing and prostitution. What Venkatesh is able to develop, through the view J.T. grants him, is a new way of thinking about the ghetto and ghetto crime, as the consequences that come when morality is uncoupled from the law.

J.T. is a good tutor. He is a learned and steady bureaucrat of the drug trade, a man with some college and management experience behind him. Most of his life is spent dealing with, somewhat endearingly, the small headaches of petit bourgeois career life— managing less-than-competent subordinates, handling the objections of Taylor Homes residents, and trying to restrict police access to the project.

J.T.’s enterprise depends on two things: the continued and deliberate ignorance of the police, and the goodwill of residents, who might summon the police and thereby make that ignorance impossible. His time (or, at least, the portion of it that he lets Venkatesh see) is largely spent managing the populace and controlling the petty criminals—the addicts, the prostitutes, the homeless—who might cause a police-drawing nuisance. He endows the local basketball games, throws parties for the project, runs voter registration drives, and keeps the local pastor, who serves as a paid mediator when the gang wars threaten to grow out of control, on the payroll.

When J.T. is forced to send his men to fight with another drug gang, the conflicts are almost never about territory—a system that was sorted out long ago—but about trivial matters involving the groups’ most volatile junior members: a fleeting disrespect; two men in different gangs liking the same girl at school. It is both necessary that J.T. protect his men in these fights—death, of course, would bring the police to the project, which would be bad for business—and also endlessly wearying.

Venkatesh occasionally has pangs of guilt that he’s participating in a kind of ghetto pornography: during the week, he watches crimes be committed without doing anything to help, and scribbles down titillating details of ghetto life; then, on the weekends, he partners with William Julius Wilson at the golf course. In the beginning of his story, Venkatesh is living in down-and-out grad student circumstances, and his concerns seem a little blown out of proportion. But as the book progresses, as Venkatesh wins accolades for his research and comes to the projects less, you see the blunt transactionalism of his position a little better—no one from the project is leaving with him. But these kinds of pangs are proof of the worthiness of his assignment. The intimacy that makes Venkatesh uncomfortable makes what he sees revelatory.

Some reviewers have objected to Venkatesh’s self-promotion. (It is also hard not to be a bit skeptical of the marketing aggression of an author who has introduced the same basic material to the public three different times.) A more substantive complaint is that because so much time has elapsed since Venkatesh did his basic research (the Robert Taylor Homes, in fact, were evacuated in 2005, and torn down last year), and since that research was done at the height of the crack epidemic, it’s difficult to know whether to regard the culture he describes as a continuing feature of the ghetto or a discrete moment in time that has already gone by.

These objections feel like small-hearted quibbling to me. One of the more devastating passages in Venkatesh’s memoir describes a run-in with a retired gangster who still lives in the Taylor Homes. The gangster recalls prior generations of hoodlums in the projects, of madams and pimps running girls out of their apartments, and of, at the fringes, the leering menace of the upand-coming young guns. Venkatesh, as an outsider listening in, feels as if only a few peripheral details have changed over the years: the particular drugs sold; the names of the gangs and the gangsters; and, perhaps, the intensity of the violence. But he suspects that there is a quasi-permanence to this culture—a culture that operates across the line distinguishing what is legal from what is not—that extends all the way back to the Great Migration. The enormous strength of Venkatesh’s work is that he makes this account resonant and believable. In this light, it is hard to charge him with dwelling too excessively on a moment in the recent past. It’s no great sin for Venkatesh to repeat the truth, particularly when the truth is so committed to repeating itself.

When Steven Leavitt, the University of Chicago economist who was the brains behind Freakonomics, decided to make his account of Venkatesh’s work a chapter in his book, he was enthralled with certain parts of the Taylor Homes research—specifically, the idea that drug dealers in the projects weren’t, for the most part, getting rich. (The chapter on Venkatesh was called “Why Do Drug Dealers Still Live With Their Mothers?”) At one point, as a kind of going-away present, J.T.’s deputy permits Venkatesh to look at the gang’s books—the precise detailing of who got paid, what bribes went to whom, how much the product cost J.T., and what it sold for. Venkatesh discovers that while most senior members of the Black Kings do very well, everyone else does pretty badly, continuing to work for what is in most cases no more than they’d make at McDonald’s, with very little hope that their incomes will ever improve.

But the insight that low-level criminals are far from glamorous figures, and that small-time hoods don’t operate in their own best fiscal interests, wasn’t original to Venkatesh—nor was it news to most of the country when Freakonomics was published. What was genuinely new and different about Venkatesh’s research had less to do with gangsters like J.T. and more to do with project residents like a fifty-year-old woman whom Venkatesh calls Ms. Bailey.

Ms. Bailey is the president of the tenants association in one of the project buildings, and the tenants’ representative to the city government; she secures new doors for broken-down apartments, and convinces local stores to donate food for children left hungry by drug-addicted parents. But she’s also a practiced shakedown artist, collecting a cut of the take from the illegal businesses that women run in the project. She has access to the list of tenants and apportions vacant apartments for use as crack dens or safe houses. In a kind of tense symbiosis, Ms. Bailey and J.T. run the whole project.

At one point, Venkatesh watches Ms. Bailey at a tenant’s meeting:

Tenants accused Ms. Bailey of going soft on J.T.’s gang and personally benefiting from her alliance with them. Ms. Bailey replied that her job was to help the tenants, period, and if that meant finding creative solutions to a multitude of problems, then she needed to be allowed such flexibility. To nearly every tenant who complained, Ms. Bailey could cite an instance of giving money to that person for rent, for a utility bill, or for food and furniture. She clearly knew how to play the influence game.

Venkatesh leaves the meeting discouraged. Ms. Bailey is the establishment—or as close as it gets in the Taylor Homes. And the establishment has caved in.

Some cities around the country have seen a dramatic spike in the murder rates in the last few years, and the conversation in policing circles has begun to shift from the matter of gangsters to the matter of neighbors. Why is it, police officials like Sylvester Johnson, Philadelphia’s police commissioner, have asked, that neighbors who see their communities wrecked by drug violence don’t speak out against the criminals? Why, in neighborhoods where many incentives cut the other way, does a no-snitches ethos still prevail?

Part of it has to do with the frail presence of police in the projects, and their inability to guarantee the safety of their informants. The residents of the Robert Taylor Homes, in Venkatesh’s telling, have regular contact with only two officers: one is a valuable local mediator, and the other regularly shakes down the drug dealers. Clearly, this small show of force is not enough. But Venkatesh suggests that the problem has deeper roots as well. When a community’s trust of the police and the instruments of law has fundamentally eroded, the distinction between what is legal and what is illegal becomes meaningless, and the community turns to less credentialed but more reliable enforcers of local rules and mores—in the case of the Taylor Homes, this means J.T. and Ms. Bailey. Venkatesh spends much of Gang Leader for a Day describing how far he’s come from his original survey questions, but at the end he returns to them and finds, ultimately, that this is what makes the ghetto different.

It is also what isolates it. By the book’s conclusion, J.T. has left the ghetto and the game, and has found a modest middle-class existence, first starting a barbershop (which fails), and then working in his uncle’s dry cleaning shop. Great gangster characters are always accomplished, melancholic self-eulogizers, and J.T. is no different: “Man, as long as I’m not behind bars and breathing, every day is a good day.” For all the talk about the financial sophistication of the drug trade, and the ways in which its most successful practitioners are the CEOs of the ghetto, a dry cleaning business seems about right for J.T. The drug trade’s economics are basically limited to the drug trade, and its lessons and practices are, in the end, only its own.