What the CDC checklists say
- By 4 months"Chuckles (not yet a full laugh) when you try to make her laugh"
- By 6 months"Laughs"
- By 9 months"Smiles or laughs when you play peek-a-boo"
CDC milestones show what most children (75% or more) can do by each age, so many children do these things sooner.
The CDC says you know your child best. If your child is not meeting one or more milestones, has lost skills he or she once had, or you have other concerns, act early: talk with your child's doctor and ask about a developmental screening.
Related milestones
Frequently asked questions
When do babies laugh?
The CDC lists chuckling (not yet a full laugh) by 4 months and laughing by 6 months.
When should I talk to a doctor?
The CDC says to act early if your baby is not meeting one or more milestones, has lost skills they once had, or you have other concerns. Talk with your child's doctor; you know your baby best.
Sources: CDC, "Learn the Signs. Act Early." milestone checklists. Checked October 17, 2026. Not medical advice. Our sources.