It's a problem every mother grapples with: When is it appropriate to step in and offer advice to another parent during a child's meltdown, and when is it best to keep your concern to yourself and mind your own business?
Actress Liv Tyler reportedly faced this very dilemma recently when she witnessed another woman scolding a screaming toddler, according to celebrity photo agency X17 Online.
Photos snapped by the agency show Tyler getting into a shouting with a woman who had allegedly been shouting and hitting the young child in the photo, who reportedly cried in his stroller.
Tyler told X17 photographers, "When I saw that, I couldn't take it. I had to do something," according to the agency's report.
Calls made to Tyler's rep by ABCNews.com were not immediately returned. The actress has a 4-year-old son, Milo, with her estranged husband British musician Royston Langdon.
Mothers told ABCNews.com that deciding when it's appropriate to step in and offer parenting advice to another mother or father is a "touchy" subject, but many acknowledged that it is sometimes hard to resist.
"This is a tough one," said Carina Schott, a 44-year-old mother of two children, ages 3 and 7. "I am all for supporting people listening to their own instincts while parenting, and I'm also sure that we have all seen this kind of situation and then kicked ourselves after walking away without saying anything."
"I think that most often you have to trust that the parent is doing the right thing, but if it's obvious that there is some kind of abuse at stake there is nothing wrong with telling the parents that there is another way to deal with their anger than taking it out of on the kids," said Schott, who blogs for Nonchalantmom.com.
"Then maybe you yourself will get punched in the eye, but at least you tried!" she said.
Parenting expert Maria Bailey said that stepping in when a parent-child altercation has escalated is not always a bad idea.
"My opinion is that if a mom is either verbally abusing or physically putting them at harm then I think it's appropriate to intervene," said Bailey, the author of author of several parenting books and the host of Mom Talk Radio.
Jamie Reeves, a 39-year-old mother in Nashville, Tenn., said she recently had the experience of witnessing an interaction between a father and his daughter that made her later regret that she hadn't intervened.
"The child was upset and her father was sort of dragging her to the car," said Reeves. "I started to say something but then stopped myself, and later I wished I had."
"I think when you're a parent you kind of that kind of built in intuition when something isn't right," said Reeves.
Moms Police Each Other's Nannies
Asked what she would have said had she spoken up at the time, Reeves said she was debating saying something like, "Hey, is everything OK?"
"There is a line that I think people can cross where it's obvious that they're losing it," said Reeves. "Everyone loses their temper or patience with their child but there comes a point where you can just sense that the person has crossed that line and maybe they need someone to just say something to calm them down."
Chicago mom Serena Beltz faced a similar situation when she spotted a nanny neglecting her charge who was about to use a black permanent marker to color her expensive-looking white dress and high-end designer stroller.
"I wish I had said something," said Beltz, 39, who added that she didn't because she was still a new mom and that today her reaction would likely be different.
Today Beltz is a member of a community message board in her Chicago neighborhood that reports on nannies and caretakers who are neglectful on the playground.
"People need to be aware," said Beltz. "When anything happens at the park the thread on the site gets longer and longer parents will watchdog and try to find the parent whose nanny [is misbehaving]."
Bailey said online message boards like Beltz's can be helpful for mothers who are concerned about their children's caretakers.
"I think that these sites are actually a good idea because moms can't be everywhere at once, so whatever moms can do to support each other is a good idea," said Bailey.
Easier With Friends
Not all mothers believe it's appropriate to comment on other's parenting. Leah Klein, a mother of two toddlers from Boston, said she does not agree with parents who intervene in other people's lives.
"I don't think its appropriate," said Klein. "More often than not, a passby does not have the big picture and how each family manages parent-child conflict or interventions is cultural as well as family specific."
Klein added that if it was a friend who she felt was mis-treating her child she'd be more inclined to speak up.
"If it is a friend or someone you know quite well, see if you can talk with the parents about how they are doing to get at the root of the problem and then, at a later time, maybe lend a book or forward a link as a resource to help them," she said.
"Don't overdo it though," said Klein.
'God, You're Mistreating Your Child'
Ilina Ewen, a mother with two children who blogs for the Deep South Mom's Blog from her home in Raleigh, N.C., said that barring an extreme situation she wouldn't intervene in another parent's situation either.
"I'd never come out and say, 'God, you're mistreating your child,'" said Ewen.
Ewen said that she often uses the tactic of distracting the child with a snack or even offering that she watch the parent's child so that the tension can be broken.
"I've said before to another mother, 'I've so been in your shoes -- if you want to take a break I can watch your daughter,'" said Ewen.
While Ewen does say that she wishes parents weren't so judgmental of others she admits that she too is guilty of occasionally eyeing other mothers and fathers on the playground.
"I think we do tend to judge, but it's often because we see ourselves in whatever it is we're witnessing."