Sitting on a sagging milk crate at Sixth Avenue and 8th Street, Mitchell Duneier doesn’t quite fit in with the homeless used-magazine vendors on either side of him. If his horn-rimmed glasses and purple button-down shirt don’t mark him clearly enough as an outsider among these street-corner entrepreneurs, Duneier’s academic credentials seal the deal. “I went for two and a half years to Northwestern,” he says. “Never got a bachelor’s degree, and then I moved on to the University of Chicago to get my Ph.D… .”

Further highlights of the 38-year-old’s CV include law school at NYU; a first book, Slim’s Table, optioned by Spike Lee; and simultaneous tenure in the sociology departments at the University of Wisconsin and U.C. Santa Barbara. But before Duneier can elaborate, a gray-haired pedestrian in a denim jacket interrupts. “How much are the Goldmines?”

To research his new book, Sidewalk, Duneier spent much of the past three years on this corner selling magazines picked from the trash. Today he’s just back to visit – distributing copies of the book to the street people he depicts in it – but he’s been pressed into temporary service while the table’s two proprietors run errands.

“Mitch’s book is going to open people’s eyes to the fact that we’re working hard out here,” says Ishmael Walker, whose difficulties with the police make for some of the book’s most poignant material. “I hope it does well.” With good reason: Duneier is sharing his royalties with its 21 main characters.

Last year, the professor brought three of his subjects to Santa Barbara as guest speakers in his class “The Life of the Street and the Life of the Mind in Black America.” “I didn’t go to high school or college,” says Alice Morin, who sells used books across Sixth Avenue from Walker’s table. “And now I’ve – what do you call it? – lectured.” Nor was Morin, who spent two weeks at Santa Barbara, altogether impressed with what she saw in the classroom. “I said to Mitch, ‘I don’t know how you deal with these kids.’ They were eating chips and talking while he was teaching!”

By contrast, the West Village reading public – housed and homeless alike – is far more polite. “Excuse me, are you the author of Sidewalk?” asks a disheveled young woman, flashing Duneier a gap-toothed smile. “I’ve been reading it.”

“Hey, I saw your picture in Sidewalk!” calls out a dog walker to Mudrick Hayes, a prominent figure in the book, as he straightens a pile of Wired back issues. “Can I get an autograph?”