Ready to roll...and sit and stand. Find out when he'll be mobile with our guide to your munchkin's major moves.

Getting Going

W hen my son was 6 months, I wondered when he'd crawl on all fours, rather than perform a one-arm rudimentary freestyle stroke to slither across the room. Then I worried that Eric's wacky crawl would turn into a funky walk. My fears were groundless: Eric walked on schedule with a perfect gait, and now, at 9 years old, he's a competitive swimmer with a strong freestyle stroke! Babies tend to master the gross motor skills in a predictable order, but when will they happen and what will they look like? That's a wild card. Learn the leaps your little one will take with this timeline.

birth to 2 months

Wiggle Worms

Your newborn hasn't figured out how to tell her muscles that she wants to move, so don't expect any purposeful gestures. "Most of their gross motor movements are primitive reflexes," says Meghan Treitz, M.D., a pediatrician at The Children's Hospital of Colorado, in Aurora. For instance, your baby may automatically spread her arms out at the sound of a loud noise or in response to other changes in her environment. That said, most infants can turn their head when lying on their back and bring their hands to their mouth. In order to progress to more advanced motions, your baby will need to develop her core strength. Build it with a daily routine of supervised tummy time, starting the first day home. Begin by placing Baby on her belly a few times a day, and gradually work up to an hour (broken into several smaller increments) by 3 months. Any position in which she's on her stomach counts, such as setting her facedown across your lap, says Lori Walsh, M.D., a pediatrician at Children's Memorial Hospital, in Chicago. If she gets fussy, stop, and try again when she's fed, alert, and happy.

3 to 5 months

Roll Over

Looking for action? By 3 to 4 months, babies begin discovering what their body can do; you can see their experiments when they wave their arms and kick their legs while in a play yard. When you smile in reaction to such feats of strength, your babe is inspired to try again. He may hold his head up when he's in your arms or prop himself up on his forearms while on his belly. He can also coordinate his hands with his eyes—perfect for swiping at a mobile or necklace you dangle overhead. This increased movin' and groovin' is part mental development, part core strength. Many babies roll from front to back at around 5 months, and after that, from back to front. (It's physically easier to roll from front to back. Try it!) "Rolling always starts suddenly, so it's important that you keep your baby closely supervised at all times," Dr. Treitz cautions.

6 to 8 months

Sitting Pretty

While most 6-month-olds will sit up without toppling in a high chair, if you put them on the floor without back support, they'll lean forward using their hands for balance. By 7 months, most will sit unassisted.

Meanwhile, some babies have gone mobile. Your cutie may do the combat crawl: With her pelvis and legs on the floor, she'll use her forearms to pull her body forward, like a marine slogging through a swamp. Or she may slither like my son did. What's with all the kooky crawlers? "There's no exact answer," Dr. Walsh says. "Crawling is one area where what looks strange is very normal." Through your tone of voice and hugs, cheer your baby on for whatever position she chooses. "Infants look to their caregivers for reassurance," Dr. Walsh says. "Your encouragement gives her the confidence she needs to move on to the next milestone.

9 to 12 months

Stand Tall

Commando Crawler, meet Speed Racer! Most 9-month-olds are masters at moving on their hands and knees. Get down on the floor and crawl next to your tot, hurrying up and slowing down to make it a game. But don't panic if precious doesn't crawl at all: "It's not a prerequisite for walking," Dr. Treitz says. "The important thing is that your baby is able to strengthen his body as he prepares to walk." One way to do this? Pulling to a stand. Cruising (using furniture for support) or walking while holding your hand is next, but it might be a month or more before he steps out on his own. Once he's found his footing, offer him a pull toy to drag around. This helps him improve muscle control and balance, which promotes a steady gait.

13 to 15 months

Walk On By

Toddlers are in perpetual motion! One minute, your tyke is crawling up the stairs; the next, she's climbing on the sofa. Most babies are walking at this point, and some are even running. "Parents should introduce new ways to play, then wait to see what their child enjoys," explains Claire Lerner, director of parenting resources at Zero to Three, in Washington, D.C. The options are endless! Turn up the tunes and dance, build a pillow obstacle course for Baby to navigate, or show her how to jump like a frog when you're at the zoo. As Lerner says, "You want your child to experience movements that will boost balance and coordination in a way that's fun for her."

Originally published in the May 2011 issue of American Baby magazine.

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