Wendy Sue Swanson, a pediatrician in Seattle, knows that a 9-month-old baby can perform some basic acts of imitation. You might expect smiling, blinking and some other facial expressions and gestures. But you know what she’s seeing a lot of?

“I ask parents if their child pretends to talk on a cellphone,” Dr. Swanson said. “Almost all of them do.”

Now, 9 months may be a little young, but if you’re a parent, at some point you are going to have to deal with the question of whether to give your child a mobile phone.

Unlike R-rated movies or a learner’s permit, there are no clear rules that dictate when a child can or should have a phone. “Like any parenting issue, everyone has an opinion,” said Dr. Swanson, who writes a blog about parenting and health for the Seattle Children’s Hospital.

But Dr. Swanson suggested that there was some consensus developing that the 11- to 13-year-old age range is an acceptable time to equip your child with a phone. This lines up with what many families are doing: A 2009 survey showed that the majority of children who have a cellphone get one by the time they turn 13.

But what kind of phone should you get, and what can you do to your child’s phone to help manage its use?

For starters, it seems fairly ridiculous to equip your 11- or 12-year-old with a full-fledged smartphone. Its myriad capabilities, combined with a child’s — let’s call it what it is — terrible judgment is a recipe for headaches at best.

There are specialized cellphones-for-children providers like Kajeet, which promise easy family controls. But the major wireless carriers also offer phones and services that basically do the same thing. One thing you may want to consider is getting your child a prepaid phone, which you can do through the major carriers or prepaid-only companies like Virgin Mobile and Metro PCS.

Given their low prices, many prepaid handsets have limited capabilities, and with a prepaid voice and data plan, there’s a built-in limit to how much your child can use the phone. Who knows? Maybe they’ll even learn the value of budgeting.

No matter what kind of handset you get for your child, you should also become familiar with the various parental controls carriers offer. Every carrier has a different combination of features and services, but generally speaking, they all are trying to do the same few things: restrict access to inappropriate apps and sites, limit usage and offer location-tracking services. Expect to pay about $5 extra a month to use these services.

If your child is using a smartphone, there are controls you can enable on the device side of the equation as well. Parents of young iPhone users should check out the Restrictions menu in Settings (go to Settings, then General, then Restrictions). After creating a password (so that little Sammy can’t undo your handiwork), you will be able to control access to individual apps, control purchases made online and disable location services for any or all apps.

Android devices don’t have built-in parental controls, but that’s easy to fix. Free apps like Android Parental Controls and apps from online security companies like Norton and Kaspersky add filtering and blocking tools so you can limit what your young mobile user encounters with his phone.

Now, you can get just the right phone, configure it just so and enable all the right services and controls, but you know that’s not going to be enough, right? The truth is, no amount of settings and preferences can replace parenting and the practice of good habits. “Don’t retreat once you’ve set it up,” Dr. Swanson advised.

And don’t let your lack of interest in or knowledge about technology create an open space for your child to explore. “You need to understand the technology as much as — if not more than — your child,” Dr. Swanson said. “It’s like learning a new language — and remember that kids learn new languages much faster than adults do.”

You may want to lay down some usage rules of your own — ones not governed by a preferences panel. One thing to consider is a curfew for any cell or smartphone use. Add to that a prohibition against any screen time — smartphone, computer or tablet — before bed. “We know that looking at a screen before bedtime inhibits a healthy sleep pattern,” Dr. Swanson said. “And we also know that getting a good night’s sleep is directly related to attention spans and classroom performance, so there’s a continuity there that you can play a role in.”

Keeping screens away from children also means keeping things like mobile phones out of their rooms at night. Keep the recharging cord in the kitchen, not your child’s bedroom. “If you don’t believe a child should have a TV in his or her room, and many parents agree with that, then there shouldn’t be a cellphone in there either,” Dr. Swanson said.

If you think about how addicted grown men and women can be when it comes to their phones, consider how much more powerful that urge can be with a child or a teenager. Neurological studies have shown that children’s and teenagers’ brains are not developed enough to always exercise self-restraint.

As with any electronic device, the goal here is to establish a sense of balance and moderation. “We want these rich experiences on earth for our children,” Dr. Swanson said. “And part of that comes from the amazing technology we have access to, and part of that is because we also turn it off.”