Two decades ago, Erika Holderness met her mom group in the most classic Baltimore way — at Harborplace.

“I was at the Gap with my daughter in her stroller, and ran into another mom who started telling me about the group,” said Holderness, who was new to the city at the time. “It was fortuitous running into her, because I didn’t know anyone and it was really helpful in getting to connect with other moms.”

Such groups can be a lifeline, because early parenting can be a singularly isolating situation where you spend most of your time tending to a needy human who can’t talk back to you. A collection of other mothers in the same sleep-deprived, unfamiliar state provides an opportunity for advice and perspective, as well as the chance for new adult friendships.

But there can be a potential downside to making those groups your sole tether to the outside world, because the honest truth about humans is that no one gets along with everyone, no matter how much you commiserate over teething.

“Just because you meet someone with kids the same age, you might not feel they’re your person,” said Clare Donofrio, a social worker at The Womb Room, a Baltimore business that provides services and support for mothers, including yoga, doulas and several groups.

And this is true whether you’re a mom in a mall or one who was in “High School Musical,” as seen in the online fervor over actress Ashley Tisdale’s recent essay in “The Cut.”

She wrote about her former group that allegedly included other famous faces like Mandy Moore and Hilary Duff. What started as finding a village devolved into what she described as mean girl high school drama that made her feel more isolated that she had before she joined.

I spoke to several local mothers who have been in such collectives, and most, like Holderness, spoke glowingly of their experiences. Others, like Jennifer Rivera of Annapolis, got lifelong friends but still found that “my experience was not that dissimilar” to Tisdale’s. Stars! They’re just like us!

It can be hard to put too much pressure on that bond if it’s the only one you’ve got. “When most of our connection lives inside a single circle, even a minor rupture can feel catastrophic,” said Allison Gilbert, who speaks and writes about loneliness and adult friendships, and co-authored “The Joy of Connections: 100 Ways to Beat Loneliness and Live a Happier and More Meaningful Life” with the late Dr. Ruth Westheimer.

“For our social health, it’s helpful to nurture connections across interests and communities,” Gilbert said.

But that can seem impossible for new moms, particularly, when that connection is the only one you easily have access to. I became a mother in my early 40s, a decade or more after many of my friends, so I lucked out by having a handful who also entered parenthood relatively late and could tell me what I was going through was normal and real. But everyone doesn’t have that.

“Socializing as a parent, especially as a mom with young kids, is very different than having a social life before you have children,” Donofrio said. “You have such a need for community as a parent, and it can be such a stressful time. You think, ‘I want to be around people who will affirm for me that it’s hard.’”

That validation was one of the things that Holderness got out of her group — it became a close circle, with members trading advice and even watching each other’s kids when running errands “or getting a little free time. It’s really hard when you’re home with the kids. Parenting is the hardest job.”

Rebecca Herron of Germantown, an actor who was seeking a local, in-person community because “all of my people were in another state,” said she figured that mom groups are “all very much like every group of girls we’ve ever been in. There are good and bad people in every organization.”

And that’s what Rivera found in her online group, connecting with mothers whose due dates were similar. “You could ask questions about things that were happening with you, and someone might say, ‘Girl, you are tripping, get thee to a doctor,’” she recalled. “You could ask about weird things that you don’t really want to ask just anybody.”

Eventually, mothers who felt particular close found each other on Facebook and formed a smaller group, including her now-best friend, that remain close to this day. “They are my village, who have my back, and I wouldn’t give it up for the world,” she said.

But other side groups formed that dissolved into “fighting and cattiness,” Rivera said, much like in Tisdale’s essay. “I don’t need to go find drama on the internet. I had enough of my own. With some groups of people, the way they bond with strangers is through a common enemy. I can see where I didn’t clock the mean girl behavior, being turned against other women, until it happened to me.”

Even with the risk of finding oneself in the middle of the kind of behavior you thought you’d left behind at graduation, all of the moms said they are glad to have found their people, even if they weren’t all the people in their groups.

“I have mom friends for life from this,” Herron said. Good friends are all any of us can hope to find, and not the kind who inspire you to write an essay in a national magazine about them.