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When do toddlers talk in sentences?

The CDC's milestone checklist lists conversations “using at least two back-and-forth exchanges” by 3 years, and “Says sentences with four or more words” by 4 years. Most children (75% or more) do these by those ages. At 3 the CDC also lists talking well enough to be understood most of the time. Worried? Talk with your child's doctor.

Checked October 29, 2026.

What the CDC's checklists say

Milestones from the CDC's “Learn the Signs. Act Early.” checklists, word for word
ByThe CDC's milestoneMonth page
3 yearsTalks with you in conversation using at least two back-and-forth exchangesYour child at 3 years
3 yearsTalks well enough for others to understand, most of the timeYour child at 3 years
4 yearsSays sentences with four or more wordsYour child at 4 years

Each row is from the CDC's checklist for that age (3 years, 4 years), checked October 29, 2026.

What “by 3 years” means

Developmental milestones are things most children (75% or more) can do by a certain age. The CDC puts each milestone at the age by which at least 75% of children would be expected to do it, so that even one missing milestone leads to a conversation with the doctor instead of “wait and see”. So “by 3 years” isn't an average. Many children do it sooner, and the checklists don't list everything a child learns.

What it can look like

Short back-and-forth conversations, then longer sentences about what happened today.

What helps

  • Ask open questions: "What did you see at the park?" and wait.
  • Add a little to what your child says: "Dog barking" becomes "Yes, the dog is barking at the cat."
  • Tell each other about your day at dinner or bedtime.

Talk to your pediatrician if…

Your child isn't doing this by 3 years, the age on the CDC's list, has lost a skill they once had, or you're worried for any reason.

You know your child best. Don't wait. 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, share your concerns, and ask about developmental screening.

If you or the doctor are still concerned, the CDC says to ask for a referral to a specialist, and to call your state's early intervention program (find the number on the CDC's list). You do not need to wait for a doctor's referral or a medical diagnosis to make this call. If your child is age 3 or older, call any local public elementary school (even if your child does not go to school there) and say: "I have concerns about my child's development and I would like to have my child evaluated through the school system for preschool special education services."

More from the CDC: Concerned about your child's development? If your child seems unwell, call your pediatrician, or 911 in an emergency.

Sources