An ongoing parenting debate about when it's appropriate to give a child a smartphone has been reignited, ironically, on social media.
Adam Grant, an organizational psychologist and professor at the Wharton School at the University of Pennsylvania, shared a post to Instagram on Monday stating his belief that parents should wait until their child is in high school to give them a smartphone.
In calling on parents to wait, Grant, a bestselling author with nearly 2 million Instagram followers, cited his own family's experience, as well as a new report that he said showed a negative correlation between mental health and getting a smartphone earlier in life.
"We were among the holdout parents," Grant wrote in an Instagram post that now has over 130,000 likes. "We know it's not easy, but the evidence is clear: even if kids under 14 need phones for communication, they don't need smartphones or social media. It's time for parents to align on waiting so it isn't just a few kids being left out."
Among the thousands of comments left on Grant's post were people on both sides of the debate, with some agreeing that no kid should have a smartphone until high school, and others arguing the decision is more nuanced than that.
"It's ridiculous to think that it's only a one household decision," one commenter wrote, in part. "When kids are surrounded by peers with some thing like a smart phone, it's impossible for them to not think that they are excluded."
"This is the world we live in now, and I don't understand why so many parents think we can ignore it or put up a united front against phones," wrote another commenter.
Some commenters shared that they want their child to be able to communicate their whereabouts with parents, while others commenters emphasized that mental health struggles cannot be blamed on phones alone.
"Great, another thing to shame parents and make them feel bad about themselves," one commenter wrote. "Why don't we focus on learning more about mental health and how to support those suffering from it rather than blaming parents for letting their child have too much screen time so the holdout parents can feel superior."
Many parents, however, shared in the comments their own experiences with waiting until their kids were older to give them phones.
"We waited till 18. They had a flip phone before that so they could reach us from anywhere. They hate social media. It worked," one commenter wrote.
"Couldn't agree with this more!," wrote another commenter. "Our 13 year old is not on smartphone or social media and it shows!"
Several commenters also agreed with the idea that parents can have an impact, with one writing, "We need more parents aligned on creating the 'norm' for smartphone use (or lack thereof)."
Grant declined to comment to ABC News.
Brooke Shannon, a mom of three daughters in Texas, is the founder of Wait Until 8th, a movement in which parents sign a pledge to not get their child a smartphone before 8th grade.
Shannon told ABC News the pledge is important because she believes it has to be a "community effort" to successfully limit young people's screen time on phones, with parents, coaches, schools and kids all on board.
According to Shannon, what started out nearly seven years ago as a small effort among the parents of her daughters' friends has grown into a national movement with over 40,000 families from across the country having signed the pledge.
"I think because so many parents struggle with this same question, it just spread very quickly," Shannon said, adding she believes the movement has also grown because of the growing body of research showing the potential impact of screen time on young people.
"There are so many studies," she said, adding, "'When you look at the amount of research, you just want to shout it from the rooftops, 'Parents just wait. There's no hurry.'"
Shannon said her oldest daughter just received her first smartphone last year, at the start of her freshman year of high school. She does not have access to the internet or any social media apps on the phone, according to Shannon.
"It's basically like a communication device, where she can text, she can call, she can FaceTime, she can listen to music and take photos," Shannon said. "That has worked really well for our family, to just take it very slowly and to keep it very simple."
Dr. Hina Talib, a board-certified pediatrician and adolescent specialist in New York City, said she hears from parents daily with questions about their teens and phones and social media.
MORE: Social media use linked to brain changes in teens, study findsShe said in her opinion, it's hard to issue a blanket age at which it's OK to give a child a phone and access to social media.
"The reality is just way more nuanced than these headlines," Talib told ABC News. "The best advice is really particular to the child in front of you. There's no doubt that social media for some teens can be harmful, but there are still groups of teens who are able to engage with their friends ... and their interests in helpful ways."
Talib said she believes a better approach is to decide on a more individual level when a child is ready for a smartphone, and then give more access to the phone with "more skills gained and responsibility earned."
"For example, you might start with just using it as a communication tool having text only or music only, and then over time, try out other applications and eventually social media," Talib said. "But even then, it should always be an ongoing, by-way communication between you and your adolescent and young adult as they continue to develop their relationship with technology."
Talib said she encourages parents to use a free 10-question tool from the American Academy of Pediatrics and AT&T to help them decide if their child is ready for a smartphone.
The tool asks questions like how often a child would need the phone to communicate with others, how responsible the child is in other activities, like turning in school assignments, and how well the child follows rules about other media, like TV or video games.
If a child is ready for a phone, the AAP also has a free tool where parents can work with their child to create a media plan that works for their own family.
Parents also have a resource through the American Psychological Association, which earlier this month issued the first guidance of its kind on teenagers and social media.
The guidance contains 10 recommendations designed to ensure that teens get the proper training on how use social media safely. For most families, that means starting with an active discussion about which sites teens are using, how often and how those experiences make them feel.
In addition to setting limits, the APA strongly encourages ongoing discussions about social media use and active supervision, especially in early adolescence. Parents are encouraged to model healthy social media use, including taking social media "holidays" as a family.
ABC News' Sony Salzman contributed to this report.