When do babies…?

Smiling, rolling over, sitting up, crawling, waving, walking and first words: the age on the CDC's checklists for each, and what helps.

Each answer here gives the age on the CDC's “Learn the Signs. Act Early.” checklists: the age by which most babies (75% or more) do it, so many do it sooner. Each page quotes the CDC's milestone word for word, says what helps at home, and when to talk to your pediatrician.

Checked October 29, 2026.

The questions

When do babies smile?By 2 months: Smiles when you talk to or smile at her
When do babies laugh?By 4 months: Chuckles (not yet a full laugh) when you try to make him laugh
When do babies hold their head up?By 2 months: Holds head up when on tummy
When do babies coo?By 4 months: Makes sounds like “oooo”, “aahh” (cooing)
When do babies roll over?By 6 months: Rolls from tummy to back
When do babies sit up?By 9 months: Sits without support
When do babies crawl?By 1 year: Pulls up to stand
When do babies babble?By 9 months: Makes a lot of different sounds like “mamamama” and “bababababa”
When do babies respond to their name?By 9 months: Looks when you call her name
When do babies play peekaboo?By 9 months: Smiles or laughs when you play peek-a-boo
When do babies get shy with strangers?By 9 months: Is shy, clingy, or fearful around strangers
When do babies pull up to stand?By 1 year: Pulls up to stand
When do babies wave?By 1 year: Waves “bye-bye”
When do babies say mama or dada?By 1 year: Calls a parent “mama” or “dada” or another special name
When do babies clap?By 1 year: Plays games with you, like pat-a-cake
When do babies cruise along furniture?By 1 year: Walks, holding on to furniture
When do babies walk?By 15 months: Takes a few steps on his own
When do babies start talking?By 15 months: Tries to say one or two words besides “mama” or “dada,” like “ba” for ball or “da” for dog
When do babies point?By 15 months: Points to ask for something or to get help
When do babies understand no?By 1 year: Understands “no” (pauses briefly or stops when you say it)
When do babies recognize their parents?By 2 months: Seems happy to see you when you walk up to her
When do babies look for hidden toys?By 9 months: Looks for objects when dropped out of sight (like his spoon or toy)

A word about “by”

Developmental milestones are things most children (75% or more) can do by a certain age. The CDC chose 75% so that even one missing milestone is a reason to talk with the doctor, rather than to wait and see. If your child isn't doing something by the age on the list, has lost a skill, or you're worried, the CDC's advice is “Don't wait.”

Sources

CDC, Key Points about CDC's Developmental Milestone Checklists (checked October 29, 2026)
CDC, CDC's Developmental Milestones: Concerned about your child's development? Act early. (checked October 29, 2026)