A new report from the Pew Internet & American Life Project finds that 78 percent of young people, ages 12 to 17, now have cellphones. Nearly half of those are smartphones, a share that’s increasing steadily — and that’s having a big effect on how, and where, many young people are accessing the Web.

The survey, released Wednesday, finds that one in four young people say they are “cell-mostly” Internet users, a percentage that increases to about half when the phone is a smartphone.

In comparison, just 15 percent of adults said they access the Internet mostly by cellphone.

“It’s just part of life now,” says Donald Conkey, a high school sophomore in Wilmette, Illinois, just north of Chicago, who is among the many teens who have smartphones. “Everyone’s about the same now when it comes to their phones — they’re on them a lot.”

He and other teens say that if you add up all the time they spend using apps and searching for info, texting and downloading music and videos, they’re on their phones for at least a couple of hours each day — and that time is only increasing, they say.

According to the survey, older teen girls, ages 14 to 17, were among the most likely to say their phones were the primary way they access the Web. And while young people in low-income households were still somewhat less likely to use the Internet, those who had phones were just as likely — and in some cases, more likely — to use their cellphones as the main way they access the Web.

It means that, as this young generation of “mobile surfers” grows and comes of age, the way corporations do business and marketers advertise will only continue to evolve, as will the way mobile devices are monitored.

Already, many smartphones have restriction menus that allow parents to block certain phone functions, or mature content. Cellphone providers have services that allow parents to see a log of their children’s texts. And there are a growing number of smartphone applications that at least claim to give parents some level of control on a phone’s Web browser, though many tech experts agree that these applications can be hit-or-miss.

Despite the ability to monitor some phone activity, some tech and communication experts question whether surveillance, alone, is the best response to the trend.

Some parents take a hard line on limits. Others, not so much, says Mary Madden, a senior researcher at Pew who co-authored the report.

“It seems like there are two extremes. The parents who are really locking down and monitoring everything — or the ones who are throwing up their hands and saying, ‘I’m so overwhelmed,'” Madden says.

She says past research also has found that many parents hesitate to confiscate phones as punishment because they want their kids to stay in contact with them.

“Adults are still trying to work out the appropriate rules for themselves, let alone their children,” Madden says. “It’s a difficult time to be a parent.”

And a seemingly difficult time for them to say “no” to a phone, even for kids in elementary school, where the high-tech bling has become a status symbol.

Guidance from parents, teachers and other adults can be lacking, says Danah Boyd, a senior researcher at Microsoft Research who specializes in teens and their tech-driven communication.

“For the last decade, too much of the online safety conversation has focused on surveillance. Surveillance will not help in a world of handhelds, but conversation will,” says Boyd, who’s also a research assistant professor of media, culture and communication at New York University.

She points to research by Henry Jenkins, the director of the Comparative Media Studies Program at the Massachusetts Institute of Technology. He has long encouraged parents, schools and after-school programs to focus on how to navigate the online world — from developing judgment about credible online sources to using high-tech skills to help build community and pool collective knowledge.

Last fall, Stephen Groening, a film and media studies professor at George Mason University in Virginia, taught a class that examined “cell phone cultures.” Students did much of the class work using phones — creating video essays, taking pictures, texting and tweeting.

“I’ve had students tell me that they bring their cell phones in the shower with them. They sleep with them,” Groening says, noting that he never knew a student attached to a laptop in that way

In New Jersey, Seton Hall University gives incoming freshman a free smartphone for the first semester. Among other things, they use them to help navigate the campus, connect with other students and follow campus news that streams on the SHUmobile app.

Kyle Packnick, a freshman at Seton Hall, liked having one of the phones and said they’re particularly helpful for students who don’t come to school with a smartphone.

But he also thinks people his age could do a better job setting their own limits with technology — and is grateful that his parents didn’t even allow him to text on his cell phone when he was in high school. He was only allowed to make phone calls.

“At the time, I definitely wasn’t happy about it,” the 19-year-old says. But now he feels he’s less dependent on his phone than his peers.

Pew’s findings are based on a nationally representative phone survey of 802 young people, ages 12 to 17, and their parents. The report, a joint project with the Berkman Center for Internet & Society at Harvard University, was conducted between July and September last year. The margin of error was plus-or-minus 4.5 percentage points.