Developmental milestones are abilities that most children can do by a certain age. CDC groups them across how a child plays, learns, speaks, acts and moves. Watching these areas over time can help parents describe progress clearly and recognize when a conversation with a health professional should happen promptly.
CDC provides milestone checklists for 2, 4, 6 and 9 months; 1 year, 15 months and 18 months; and 2, 2½, 3, 4 and 5 years. Each age page is a practical observation aid. It is not a scorecard and should not be used to compare children casually.
What does a developmental milestone describe?
A milestone describes an observable skill or behaviour. It might concern social interaction, communication, problem-solving or movement. Looking across several areas gives a more useful picture than focusing on one isolated ability.
Children develop within relationships and daily routines. Parents often notice new skills during feeding, play, dressing, conversation and time with other people. Recording examples can make a discussion with a clinician more specific: what the child does, what is difficult, when it was first noticed and whether the pattern is changing.
How should families use the checklist?
Choose the checklist that matches the child’s age and mark skills you have actually seen. Use it as a starting point for conversation at routine visits and whenever a concern arises. CDC also provides a Milestone Tracker app, printable checklists and activity suggestions.
If a child was born more than three weeks early, CDC’s checklist instructions explain using corrected age until the child is 2 years old. Corrected age accounts for the number of weeks the baby was born before 40 weeks. A clinician can help if the dates or the appropriate checklist are unclear.
Is milestone tracking the same as developmental screening?
No. CDC states that its checklists are not a substitute for standardized, validated developmental screening tools. Tracking is an ongoing way for families and professionals to observe development. Screening is a more formal process using a validated tool to identify whether further evaluation may be needed.
CDC reports that the American Academy of Pediatrics recommends general developmental screening at 9, 18 and 30 months and autism screening at 18 and 24 months, or whenever a parent or provider has a concern. A screening result does not by itself establish a diagnosis; it helps determine the next step.
What if one milestone has not appeared?
A single unchecked item does not explain why a child has not shown that skill. The useful next step is to share the observation rather than wait for certainty. CDC advises families to act early if a child is not meeting one or more milestones, has lost skills once present, or if the family has any other developmental concern.
Tell the child’s doctor or another appropriate health professional exactly what you have noticed and ask about developmental screening. Bring the completed checklist and examples. If concern remains, CDC advises asking for referral to a specialist who can evaluate the child more closely.
Why does loss of a skill matter?
Development is not always perfectly even, but losing a skill that was previously used is different from taking longer to acquire it. CDC specifically includes loss of skills among the reasons to act early. Document what changed and when, and contact a health professional rather than relying on an online checklist to interpret it.
What are early intervention services?
CDC directs families in the United States to early intervention programmes for children under 3 and to the local public school system for children aged 3 or older. Service names and access routes differ by country. The general principle is that families do not need to wait for every question to be resolved before asking what developmental support is available locally.
Evaluation may show that development is on track, that monitoring is appropriate, or that targeted support could help. The checklist cannot predict which conclusion applies to an individual child.
CDC’s approach places parents and other caregivers in an active role because they observe the child across many ordinary situations. Their concerns are useful clinical information. Families do not need to prove that a condition is present before raising a question or requesting screening.
How can parents prepare for an appointment?
- Complete the age-appropriate checklist using skills you have observed.
- Write down examples, dates and any skills that have been lost.
- Note questions about hearing, vision, movement, communication, play or behaviour.
- Share observations from other regular caregivers when relevant.
- Ask whether standardized screening or referral is appropriate.
Videos can sometimes help demonstrate a behaviour that does not occur during the visit, provided recording is safe and respectful. A clear record supports the clinical conversation but does not replace direct assessment.
How can activities fit into everyday life?
CDC’s age pages include simple activities families can try. These suggestions are opportunities for responsive interaction, not tests that a child must pass. Talking, playing, reading and responding to the child’s interests can be woven into ordinary routines. Stop an activity if it causes distress and discuss persistent concerns with a professional.
What should families remember?
Milestones help organize observations; they do not label a child. Use the age-specific list, notice patterns across developmental areas, and share concerns promptly. Acting early creates time for proper screening, evaluation and support when needed.
References
- Centers for Disease Control and Prevention. CDC’s Developmental Milestones. Source reviewed 4 October 2026.