Those were the days. (Were they really the days?) Yes, they were, at least according to the pilot episode of CBS’s enjoyably swinging new series “Swingtown,” which takes us back to the summer of 1976, when Quaaludes, martinis, health shakes, cigarettes, open marriages, jogging, orgies, and un-self-conscious patriotism all blended into a hedonistic swirl. This, after all, was the decade when Jimmy Carter confessed to having “lust in [his] heart” to Playboy magazine, so why shouldn’t everyone else, women included, let loose their inner Hefner?

“Swingtown,” which makes its premiere Thursday at 10 p.m., opens on an airplane, now a locus of claustrophobia, entertainment screens, and dread. Less so then. Captain Tom Decker (Grant Show), a handsome man of about 40 with a hectic sex life, calmly quizzical eyes, and a flourishing mustache, is on the intercom, dressed only in a sleeveless undershirt following some heated action with a stewardess that has literally resulted in a burn. “Listen up, folks,” he says. “It’s time to stub out those cigarettes and finish up those cocktails. I’ve just initiated our descent into O’Hare.” Then it’s time to soothe the (young, blond) worried air hostess. “Your wife’s going to kill me,” she tells Tom. “My wife’s going to love you,” he replies.

This doesn’t turn out to be quite accurate. Trina Decker (Lana Parrilla), a 30-ish brunette with sculptural cheekbones, duly plays her role in the ensuing threesome, but then gently puts her foot down. “Let’s keep it in our age group, okay?” she says. Tom is all empathy and understanding. No problem. Anyway, Trina is much more intrigued by a couple who have just moved into the house across the street. Tom notices her looking at them through the window. “What’s so interesting?” he asks.

“Our new neighbors.”

Tom moves to the window to take a peek himself. “They look happy,” he observes.

“I was just thinking the same thing.”

The very slightly sinister undertone (do they like happy people, or secretly wish to bring them down?) in that brief snatch of conversation is a delight. The new neighbors are the Millers, Bruce (Jack Davenport) and Susan (Molly Parker). Married straight out of high school, they have a precocious teenage daughter, Laurie (Shanna Collins), who’s well up on marijuana, Henry Miller, and Anais Nin, and a younger son, B.J. (Aaron Howles), who hasn’t gotten to “Tropic of Cancer” yet but has just discovered Penthouse. Bruce has made some money, and the family’s reward is to move into a tony lakeside Chicago suburb, leaving behind their slightly put-out pals, Rick (Nick Benson) and Janet (Miriam Shor) Thompson. Susan and Janet are dear friends but they’re about to part ways, divided by that ugly little word: “status.”

“Don’t you ever get the feeling there’s something else out there, like an energy shift we’re missing out on?” Susan asks. “You know that whole biorhythm thing shot straight over my head,” Janet replies primly. “I know everything I need to know about who I am, thanks.” Susan is a late-blooming flower child in the Sissy Spacek mode, blue eyes brimming with unanswered questions, but Janet is still in the 1950s, when being good neighbors wasn’t supposed to mean you also slept with each other.

Created by Mike Kelley (“One Tree Hill,” “The O.C.”) and directed by Alan Poul (“Six Feet Under,” “Rome”), “Swingtown” will make you feel like you’re watching HBO or Showtime until you notice the presence of commercials and the absence of four-letter words and nudity. The soundtrack (coordinated by Liz Phair) is a barrage of nonstop ’70s hits, from Bruce Springsteen (“Born to Run”) to David Bowie (“Golden Years”), and the overall feel is lush, optimistic, and upwardly mobile. Of course, most of these grown-ups are dreamers, with their brains in their pants. (“Hey, Dad, what’s the last book you read?” Laurie, the Henry Miller fan, asks. “I thumbed through the shark parts of ‘Jaws,'” Dad jauntily counters. “Does that count?”) But there’s a shrewdness, too, as if all concerned (or most, anyway) have grasped that when a sexual paradise beckons, there’s no point in standing on the touchline.

The pilot episode of “Swingtown” concludes with a grand, freewheeling party held by the Deckers, to which the Millers are invited. Decorum is observed to the extent that the orgy is held in the basement rather than on the patio. Trina takes Susan on a tour of the house and follows up with a disquisition on the glories of open marriage. “Ever since Tom and I got into it we’ve reached a whole new level of intimacy — not to mention the incredible sex.” Then she opens a little pill box. “Quaalude?” she offers, extending it. The Quaalude does its job, and the party ends as Tom and Trina intended it to — with the Millers spending much of their first night in the neighborhood in their neighbors’ bed.

The most striking symptom of impending change is that the teenage children of all those swinging moms and dads are already more cynical than their elders. The girls, in particular, are much more assertive, and there’s a startling scene when a boastful 12- or 13-year-old boy gets beaten up by a slightly older girl he’s made the fateful mistake of claiming to have slept with. The fury with which she knocks him to the ground and repeatedly kicks him in the stomach is something to behold. The parents are having a whale of a time, but something darker seems to be going on with their offspring.

There’s no way of knowing whether “Swingtown” will live up to the promise of this first episode, but it’s much livelier than most new network shows. There is genuine curiosity as well as nostalgia at work here — could things really have been like this? — along with muted signs that this mini-utopia will prove as short-lived as the rest of them.

bbernhard@nysun.com