Your baby is roaring to roll over — and who can blame her? Rolling over is the first way babies can change their position in space and start to take a tiny bit of control over their world. Rolling from side to back usually happens between 1 and 5 months; rolling from back to side usually follows sometime between 2 and 7 months. Encourage your baby's attempts to roll by talking her through it and enticing her — put your face or an interesting toy just out of reach.
Of course, once your baby can roll, she can also easily tumble off a changing table (or any other surface), so keep your hands on her and use a restraining strap whenever she's off the ground. Some babies enjoy rolling so much that they really develop it into a standard form of transportation. Rather than crawling, they learn to roll everywhere, exploring their world with great adeptness. It's amazing to watch your baby solve the problem of how to get around on her own!