‘I miss the diversity”: That’s what parents who’ve just moved to the suburbs inevitably tell me. Sure, we have backyards and more bedrooms and nice kitchens and decent public schools. But Scarsdale (or Larchmont or Briarcliff) . . . well, as one mother says of her new neighborhood in Connecticut: “It feels like ‘The Stepford Wives’.”

In the past decade or so, more and more urban couples have decided to stay put even after they have kids. They’re willing to sacrifice space for some of that diversity — as long as there’s a decent public school around.

For such parents, Park Slope is paradise: You can walk to everything (while schlepping 30 pounds of groceries), your kids can play in Prospect Park (not by themselves, of course) and the building has other rugrats (but nowhere to park the half-dozen strollers). And you can get diversity and a good elementary school.

Or could, until overcrowding struck.

Last week, the Park Slope Community Education Council approved a rezoning that effectively cuts 10 blocks worth of families out of PS 321, one of the city’s most coveted elementary schools. Kids on those blocks who haven’t started school yet will mostly be sent to a new school opening up on more-recently-gentrified Fourth Avenue.

Things got heated at a meeting last month on the new zoning; a police officer had to get between a parent and a council member.

Families worry about falling property values (three real-estate agents refused to comment to me), but keeping the kids at PS 321 is the bigger issue. Some “dezoned” parents are even talking about renting apartments inside the 321 zone for a year so their children can be grandfathered in.

Ray is in contract to buy an apartment in the unlucky 10-block area. His older son starts kindergarten in 2014. He hopes the new school will be good — the assistant principal at 321 is supposed to become the principal there. But he’s also checked out the local Catholic schools and discussed the finances of private schooling with his parents, just in case.

The new school will be more “socioeconomically diverse,” Ray acknowledges, because the blocks are further away from Prospect Park.

But aren’t Park Slopers looking for diversity? Writing at Park Slope Patch last year, neighborhood resident Louise Crawford asked parents and leaders “What Matters to Park Slope.” From the president of the Park Slope Civic Council to the head of the advocacy group Park Slope Neighbors, diversity topped nearly everyone’s lists.

Crawford, whose two children graduated from PS 321 and who is the author of onlytheblogknowsbrooklyn, tells me that because of its progressive politics, the neighborhood has “aspirations for diversity.” And that the extra diversity at 321 thanks to the families living closer to Fourth Avenue “added immeasurably to the school.”

Matthew Didner, the acting chair of a group of parents whose kids are now zoned for the new school, tells me that diversity is very important to his neighbors. “One of the things that universally has been bemoaned is that the neighborhood is becoming more homogenous.”

But let’s face it: There are limits to the diversity that Slope parents want. Few demand to be a part of the new, more diverse Fourth Avenue school.

“People want diversity, but without the risks,” explains Mike Petrilli, the author of a new book called “The Diverse Schools Dilemma.” He says upper-class parents “like racial diversity because they want their kids to be comfortable in a multiracial society, but they are not excited about socioeconomic diversity” because it will start to affect the quality of the education.

“Poor kids tend to come into a school so far behind,” he notes. Also, “parents don’t want their kids in class with kids who are experiencing tough situations at home.”

So middle-class parents who want to stay in the city and use the public schools are in a bind. The five boroughs hold only a handful of schools where they can get what they want. And buying a home in a particular neighborhood is no guarantee, as Park Slope parents just learned.

If there’s an upside to all this, it may be that middle-class urban parents will have more of an incentive to push for school reform across the board, lest they wind up heading to Stepford after all.