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.