How and when infants learn to climb stairs.

Seven hundred and thirty-two parents reported when and how their infants learned to climb stairs. Children typically mastered stair ascent (mean age=10.97 months) several months after crawling onset and several weeks prior to descent (mean age=12.53 months). Most infants (94%) crawled upstairs the first time they ascended independently. Most infants (76%) turned around and backed at initial descent. Other descent strategies included scooting down sitting, walking, and sliding down face first. Children with stairs in their home were more likely to learn to ascend stairs at a younger age, devise backing as a descent strategy, and be explicitly taught to descend by their parents than children without stairs in their home. However, all infants learned to descend stairs at the same age, regardless of the presence of stairs in their home. Parents' teaching strategies and infants' access to stairs worked together to constrain development and to influence the acquisition of stair climbing milestones.