General information only. This page explains CDC terminology about child development. It does not assess an individual child’s development.

What is developmental monitoring?

CDC defines developmental monitoring as observing how a child grows and changes over time and whether the child reaches milestones in how they play, learn, speak, act and move. Families, caregivers and early-childhood professionals can take part in developmental monitoring.

What is developmental screening?

CDC describes developmental screening as a closer, more formal look at development using a standardized, validated screening tool. Screening is different from simply reviewing a milestone checklist.

What is a developmental milestone?

CDC uses the term developmental milestone for a skill or behaviour that most children can do by a certain age. Its current milestone checklists cover development from 2 months through 5 years.

How were CDC milestone ages selected?

CDC states that milestones in its current checklists were placed at ages by which at least 75% of children would be expected to show them. CDC also states that the checklists do not contain every possible milestone a child may demonstrate.

Can a milestone checklist diagnose a developmental condition?

No. CDC explicitly states that its milestone checklists are communication tools and are not substitutes for standardized, validated developmental screening tools. The checklists can help families and professionals discuss development and identify when additional screening may be appropriate.

A webpage cannot interpret an individual child’s development. CDC advises families who notice a missed milestone, loss of a previously acquired skill or another developmental concern to discuss that concern with the child’s doctor.

Why keep monitoring and screening separate?

The distinction matters because ongoing observation and a formal screening process serve different purposes. CDC presents them as complementary parts of identifying developmental concerns early, not as interchangeable tests.

References

  1. U.S. Centers for Disease Control and Prevention. Developmental Monitoring and Screening, updated 16 February 2026.
  2. U.S. Centers for Disease Control and Prevention. Key Points about CDC’s Developmental Milestone Checklists, updated 16 February 2026.