Babies may start out pretty still, but before you know it, they're totally on the go. Check out this age-by-age guide to rolling, sitting, crawling and more.

3 to 5 months

At about 4 months, your baby figures out that with the help of his stronger torso muscles, he can turn from his stomach to his side. Not long after that, he manages (often accidentally) to roll from his side to his back. Although some infants learn to roll in the opposite direction first -- from back to belly -- for most that's a later accomplishment. In a few more weeks, your baby will likely be able to make it all the way around, flopping from belly to back to belly again. Then he may roll across the room as a way to travel.

5 to 7 months

The first time baby sits up, it'll probably be with your help. A young baby may not be strong enough yet to keep her chest raised, let alone keep her balance, so she'll likely slump or tip over. But your baby will get better at holding herself up as she approaches the middle of her first year; you'll probably see her hold her hands out in front to steady herself. As she becomes more comfortable, she'll be able to do other things at the same time -- like reach for a toy. Eventually she'll figure out how to pull up from her stomach into a sitting position and then lie down again.

6 to 8 months

Lying on his belly, your baby will experiment with different ways to move forward. Wiggling, stretching, kicking, and pushing, he'll try to propel himself with his arms -- his efforts moving him along in fits and starts. Or, he may try to creep across the floor by rocking back and forth on his stomach with his arms and legs spread out.

7 to 10 months

Once your baby's up on her hands and knees, rocking back and forth, she's getting ready to crawl. She may look like she wants to sprint forward, even putting out a tentative hand, but she's not moving anywhere just yet. Then one day she takes off. Of course, it may take her longer to get her momentum. Some babies crawl backward before going forward as they figure out how to get their legs and arms to work together. Other babies skip crawling altogether, or adopt a variation on the traditional hand-forward, then knee-forward movement. Your baby may get around by dragging one leg behind her, scooting along on her bottom, leapfrogging (hands together, then knees together), or moving forward like a crab on her hands and feet.

9 to 14 months

At about 9 months, your baby will likely try to pull himself up to a standing position. Once he's up, he might find that if he leans against the couch or wall, he can stay standing. But what goes up must come down -- and your pre-walker may not know how to lower himself. If he starts crying, help him bend his knees so he can get back down to the floor without falling.

Once your baby gets comfortable standing, he'll likely try to get around by cruising: traveling up and down the length of the couch or along the wall by holding on. He'll also enjoy "walking," clutching your hands as you keep him upright.

12 to 14 months

As your baby's balance improves, she'll occasionally let go of you (or her favorite piece of furniture) to take a step by herself, only to grab you again when she feels like she's falling. At first, she may only be able to take a step or two before losing her balance, but soon you won't be able to keep up with her. Don't worry about your baby needing the "extra support" of shoes -- in fact, they may make it harder for her to walk. But for outside walking, shoes are a must. Choose a flexible pair with nonskid soles for safety.

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American Baby