The Park Slope featured in Hal Ashby’s 1970 film “The Landlord” is a far cry from the Park Slope of today. Where are all the boutiques, the joggers, and the baby strollers pushed by yuppie lesbian couples? They’re as alien to the predominantly black neighborhood as Elgar Winthrop Julius Enders (Beau Bridges), the privileged, 29-year-old whelp who cruises into it one day to have a look at the dilapidated row house he’s just purchased. It probably cost him a week’s allowance.

Elgar is totally clueless, and everyone — in the building, in the neighborhood, in the audience — knows it from the moment he nearly steers his convertible onto the stoop. He steps out in a pristine white suit, a pot of fresh flowers in hand. Within minutes, he’s being chased down the street and his hubcaps are gone. The boy’s foolish gentrification fantasy has sprung its first leak.

Ashby’s debut film, rougher-edged and more rambunctiously political than his subsequent work (“Harold and Maude,” “The Last Detail,” “Being There”), gives this callow new property owner a comeuppance that’s also a coming of age. Kicking the tenants out of the building and turning it into a bachelor pad, Elgar discovers, isn’t as neat as he thought.

Well, duh. But though “The Landlord,” which begins a one-week run at Film Forum today, is premised on a shameless caricature of the entitled WASP, it’s awfully funny, and the goofily grinning Mr. Bridges is up to the task. Scripted by African-American actor Bill Gunn and based on a novel by Kristin Hunter, the film is, for better or worse, 100% of its time, from the jarring cuts between whitewashed squash courts and the graffiti-scrawled ghetto, to the earnest examination of burgeoning black pride and the seditious, straight-faced mockery of life at the Enders estate.

Unsurprisingly, Elgar’s real-estate venture doesn’t sit well with his parents. His father scolds him for buying a “dreadful slum” where the tenants rarely pay rent, and his mother — played with loony insouciance by Lee Grant — asks him if he remembers “Guess Who’s Coming to Dinner,” then warns: “All negroes are not like that!”

In a different context, of course, that could be understood as a rallying call. The year after “The Landlord” was released, “Sweet Sweetback’s Baadasssss Song” and “Shaft” launched the blaxploitation genre; like those films, “The Landlord” is a riposte to genteel Hollywood explorations of race that presumed the issue would announce its presence by politely ringing the doorbell. Elgar is good for laughs, but the film’s true sympathies lie with the victims of social injustice he’s never been aware of until now — those characters who haven’t, as one of them puts it, “grow[n] up casual.” They include Elgar’s mixed-race girlfriend (Marki Bey), a flirtatious housewife named Francine (Diana Sands) who resides in Elgar’s new building, her civil-rights-activist husband (Louis Gossett Jr.), and the teacher (Mel Stewart) who explains to his baffled landlord that “some people can’t learn what we learn.”

For Ashby, an award-winning film editor who landed his first directing gig at 40, “The Landlord” represented the dawn of a wildly successful decade. (The next one did not go nearly as well, and Ashby, who died in 1988, didn’t see it all the way through.) It was also the director’s first go at the theme — admittedly, not the most original one — that would dominate his filmmaking: the loss of culturally preserved innocence. “The Landlord” is far from a perfect film, and few people would call it Ashby’s best. But it has a diffuse energy, especially in the jolts of experimental editing and Ms. Grant’s delightful unpredictability, that keeps it at a safe remove from cliché. (Ms. Grant will introduce the 7:45 p.m. showing tomorrow night.) And though the zeal with which it’s delivered may feel dated, its message remains relevant today.

As for the portrayal of Park Slope as a shabby place that’s hostile to white interlopers, well, isn’t that quaint?

Through September 25 (209 W. Houston St., between Sixth Avenue and Varick Street, 212-727-8110).