Infants sometimes “crawl” with their stomachs on the ground as early as 3 months, but this crawling is infrequent with the baby remaining stationary most of the time. True crawling with the stomach off the ground and the baby frequently on the move usually develops between 7 and 11 months of age and lasts anywhere from a week to 4 months before the child switches to walking. Even after taking their first unaided steps, most babies still crawl part of the time until they have mastered walking. While crawling, infants gradually practice standing, at first by using people or objects for support and, later, without support. Crawling babies are notorious for getting into trouble, so parents are often advised to childproof their house before a baby reaches crawling age.

Though crawling is an important developmental milestone in children, it is not necessary for healthy development. Some babies skip crawling and go directly to walking. Others “bottom shuffle” instead of crawling (sometimes referred to as “bum-shuffling”, or “scooting”). Bottom-shuffling babies sit on their bottoms and push themselves forward using their legs, and sometimes their hands, often in specially reinforced trousers. Babies that bottom-shuffle tend to walk later than babies that crawl.

Whether infants crawl is also culturally determined. European parents in previous centuries discouraged it as being too animal-like.They kept their children in long dresses and other clothes that made crawling difficult or impossible. Some cultures consider it to be dirty and dangerous.