Crawling: 7 to 9 months
When your baby first tries to crawl on her hands and knees, she'll probably be stuck in neutral. Curiosity, however, will lead her to experiment with different forms of forward motion. She may push her palms against the floor (and likely scoot backward), push her feet against the floor (and fold in the middle), pick up one hand (and fall on her face), or kick her feet (and land on her face again), explains Eugene Goldfield, Ph.D., a research associate at Children's Hospital and Harvard Medical School, in Boston. Crawling can actually take on many forms: "bear walking" on hands and feet with her bottom high, pulling with forearms and belly on the floor, scooting around bottom-down, and the classic creeping on hands and knees.
Don't try to push through this horizontal phase. "There's no advantage to putting an infant in play devices or jumpers that encourage early standing," says Jane Case-Smith, Ed.D., an associate professor of occupational therapy at Ohio State University, in Columbus. Research shows that using walkers may actually delay development, because their large trays block the child's view of her moving feet, depriving her of feedback that's critical to physical and mental growth.
Skill builder: Let your baby crawl on a variety of safe surfaces: Line cushions on the floor, take her outside on the grass, or give her a gentle incline to scale.