The history of America’s exposure to Italian cinema is like the prom date who shows up all awkwardly earnest with a corsage in hand, but after a couple of drinks punches the DJ and steals a car. Between the 1960s and the ’80s, America’s genteel cultural gatekeepers ushered in a stately promenade of Italian cinema — Federico Fellini’s “La Strada,” Vittorio De Sica’s “The Bicycle Thief,” and other neorealist masterpieces from previous decades. But in the late ’80s, the home video market, hungry for content, unleashed a flood of Italian exploitation pictures.

Suddenly we realized that offerings from the Criterion Collection were only the tip of the iceberg, and that our own critics were writing reverential essays about a tiny section of Italian cinema. Italians, it turned out, had been gorging themselves on crime and horror flicks featuring orgies of destruction and eyes pierced by enormous wooden splinters in extreme close-ups. The familiar names changed from Fellini, Pasolini, and Rossellini to Argento, Fulci, and Bava. Today, a film student grabbing a random slice of Italian cinema history is just as likely to pick up “Blood and Black Lace” as “Umberto D.”

It helps, of course, that stateside DVD labels such as Blue Underground continue to release Italian gems for our edification, as it is doing today with three exploitation films of the 1970s.

The 1960s had birthed the spaghetti Western, but by the early ’70s — the “Decade of Lead,” which brought neofascist bombings and Red Brigade assassinations — it was as dead as Dillinger, and the giallo and poliziotteschi were ascending. The latter genre, defined by rough and bloody crime thrillers, was inspired by such American cop films as “Dirty Harry.” But unlike American films, there were no good guys or bad guys — everyone was shaded gray.

Set in the American West but shot in Italy, Pasquale Festa Campanile’s “Hitch-Hike” (1978) may be the best of the bunch. It’s an old chestnut of a story: A married couple, Walter and Eve, pick up a psychotic hitchhiker (going by the overly symbolic name of Adam) who proceeds to terrorize them. For audiences conditioned by decades of Hollywood convention, the film is downright shocking: no three-act structure, no sympathetic characters, no closure. Walter and Eve, in fact, are repellent. He’s a drunk, self-pitying chauvinist who likes to climb on top of his wife after a couple of cases of Schlitz; she’s a frigid scold who looks like she’s waiting to put a knife in his back. Adam, dispensing murder, rape, and random sadism, seems like just another member of the family. There’s no preaching, no message, just a camera recording man’s inhumanity to woman, and woman’s inhumanity right back.

As the Decade of Lead wore on, the movies struggled for survival as TV stations began airing hundreds of free films every week. The poliziotteschi became passé and the horror movie, with its unlimited opportunities for gore, provided the shocks for increasingly jaded viewers. Master hack Umberto Lenzi was best known for his poliziotteschi, but in 1980 he jumped in the gore pool with “Nightmare City,” an amazingly shoddy but unexpectedly entertaining zombie picture. Mr. Lenzi’s zombies are ridiculous, dressed in natty sweaters and sport coats, their faces covered with makeup that looks like strips of bacon dipped in mud; “crude” doesn’t even begin to do it justice.

One of the most distinctive Italian genres, giallo got its name from the yellow-jacketed crime novels published by Mondadori, the pulp fiction of its day.

Giallo focused on masked serial killers who split their screen time with incompetent police investigators and elaborate set pieces of murder and mayhem that brought the narrative to a screeching halt in order to show off the director’s technical virtuosity.

“Nightmare City” opens with a horde of zombies sprinting off a plane, machine-gunning the cops and taking over the local power stations and TV studios. If Italy was worried about bands of fascists overrunning the country, here was that nightmare committed to film and cranked to maximum fear. Behind the camp there was a barely concealed scream. At the movie’s climax, dozens of heads literally explode, as if the Italian mind could only take so much insanity before popping like a ripe tomato.

Known as “The Godfather of Gore,” Lucio Fulci put the capper on the era with his giallo, “The New York Ripper” (1982). The film is set in a sleazy, sin-soaked Manhattan, a heterosexual version of William Friedkin’s “Cruising,” where every character has a kinky fetish or a secret life. Released as Italy’s Banco Ambrosiano scandal was erupting in a shower of Vatican politics, Masonic cults, and executive suicides, “Ripper” was a vile movie for vile times, and it marked the end of Italian genre filmmaking before the market collapsed in the mid-1980s.

Law and order are no match for the anarchic delights of sex and violence unleashed by the serial killer in “The New York Ripper,” who talks like Donald Duck. But when his head finally explodes, it’s unclear if it’s because a bullet destroyed it, or because the pressures of a society in turmoil — he’s distrustful of its police, its laws, its church, and its government — had finally caught up to him. Never has a film industry given itself such an appropriately explosive send-off. The Decade of Lead was over, but in Italy, where the Second Mafia War, which would eventually leave more than 1,000 people dead, was heating up, the bad times were only just beginning.