When do babies began to crawl?

7-10 months: Development of gross motor skills like crawling vary from baby to baby. They can also be affected by things like prolonged illness, prematurity, any congenital bone or joint problems, weight of infant. That all being said, the typical time is between 7 and 10 months of age. This is just one skill that we assess in looking at a baby's skills. And yes, I have seen occasional baby who skips crawling.