NEW YORK — Mike Biewenga, a stay-at-home dad for the past four years, noticed something funny when he took his daughter to story time at a nearby library. Gathered around the reader in a circle, mothers sat farther from him than from other moms.

"There was a gap, then me, then a gap, then the rest of the circle," says Biewenga, 33, of Arlington Heights, Ill. "And I mean, I shave, I comb my hair. I'm a normal-looking guy."

And when Gregory Keer, a Los-Angeles area high school teacher, took his kids to a park get-together once during his years as a stay-at-home dad, he recalls hanging on the sidelines, staying away from the main conversation, because he was "not one of the girls."

This Father's Day, there will be some 159,000 stay-at-home dads across the country and 5.6 million stay-at-home moms, according to the most recent U.S. Census Bureau figures, which are from 2006. The numbers don't include single fathers, the many who work part-time, and those with kids over 15. Still, it's a small number compared to the moms. And while it's grown slightly each of the past few years, so has the number of moms.

But things have evolved, at least in terms of attitudes. Many stay-at-home dads say they feel their lifestyle choice, whether made of desire or economic necessity, is accepted much more now by friends, relatives, colleagues and strangers — even envied — than it would have been only a few years ago.

"I've had guys tell me privately that they wish they could do the same thing," says Rick Walker, 50, who's spent a dozen years as a stay-at-home dad to Nicole and Chloe, now 14 and 12, in Southlake, Texas. "But they don't know how to broach it with their wives."

Yet many also speak of a different problem: A sense of isolation in a world where mothers have their coffee dates and group playdates, but fathers often plan activities alone, or find themselves sitting on the bench, speaking on their cell phones or conversing only with their kids at playgrounds and birthday parties.

"It is kind of a lonelier experience," Keer says. He recalls it was his wife who arranged that park get-together, and assigned him to bring brownies, though he was the primary caregiver. "For me, it would have felt gender-inappropriate," he says.

For Biewenga, the isolation was a reason to create his own community of dads — AtHomeDad.org, where some 10,000 visitors a month, he says, swap stories and seek advice. "Just wondering if anyone of you have had experience or have tried using the pull-up diapers," a current post reads, signed Bob the Family Guy. The site also advertises the 13th annual at-home dads convention later this year.

'GOING NUTS'

Biewenga, who squeezed in a chat with a reporter during nap time for his two kids, found that at first, "I was going nuts being at home by myself." The exclusionary behavior from some moms — certainly not all, for he has many mom friends — didn't help.

At playgrounds, he notes, "You can be with your kid playing in the sand, and a mom will come and scoop up her kid. It doesn't happen every time. But I guess that image is there, of a guy at a playground who's a child molester."

Dads also tell of mothers being hesitant to come to their homes for playdates during the week, or to have them in theirs. Jen Singer, who has her own Web site for stay-at-home mothers, www.MommaSaid.net, says that's understandable.

"What woman wants to have a man in her house in the middle of the day when her husband is working? You'd have to have playdates in public," she says. And at the playground, she says from experience, it's awkward. "You finish talking about the kids and there you are, by the slide, wondering what to say."

Some fathers, like Adam Keeble of Allendale, N.J., feel they're accepted easily into their town's community of mothers. As the lone stay-at-home dad with a British accent in the local park, he said, so many mothers would say, "Hi, Adam" that he had to keep a book to remember names. He also has no trouble, he says, organizing playdates at his house.

Keeble, an aspiring novelist who's been home for five years, says the frustration of the job is similar to that a mother might experience. "It's the best job in the world, except when it isn't," he says. "On a sunny day with the kids playing in the sand, it's great. But then there's the miserable February day when they look at me and say, well, now what? And, well, it's only reruns of Dora."

'IN MY OWN LITTLE BUBBLE'

For most stay-at-home dads, whatever frustrations there are appear to be ease up in many ways when the kids are out of diapers and in school at least part of the day.

That's what Bob Hurley, a stay-at-home dad for seven years to his two sons, has found. He began his own stay-at-home career when he was laid off twice from jobs in the tech industry, and his wife had a good sales job. The couple didn't want to squander college money on daycare.

"It took a couple years until I felt good," Hurley says. But gradually, the awkwardness dissipated. "There are so many upsides to what is happening with the boys," he says.

And no longer does he get "that cross-eyed look" when he tells people what he does all day. Yet Hurley acknowledges a few awkward moments.

"We'll be at a party and the moms will be talking about their stuff, and the guys will be talking about their work, and I'm not really part of either conversation," he says.

Robert Baker, a former chemist and engineer, is still experiencing those first few years at home. His daughter, Kaleigh, is 3 and 1/2.

"It does feel like I'm more isolated than if I were a woman," says the father from Concord, N.H. Then again, he adds: "I don't think men seek out the same kind of networks. I'm sort of in my own little bubble."

He and Kaleigh spend a lot of time cycling into town, she in her little trailer attached to the bike, for park or library visits. Her mom would probably schedule more playdates if she were the one at home, Baker admits. "I'm, like, we're fine," he says. "There's a difference of opinion."

The isolation does take its toll by the end of the week. "By Friday, I am fried," he says. And yet, he makes it clear he feels very lucky.

"It's been a blessing," he says. "Not too many dads have this chance. One day I am going to look back and say: Wow."