Should my child have a CDI assessment?

Wondering whether a CDI could help you understand your little one's words and gestures? Here's exactly what it is and when it helps.

In short

The MacArthur–Bates Communicative Development Inventories (CDI) is a parent-completed checklist that captures how your young child understands and uses words, gestures and early sentences — usually between about 8 and 30 months. It's gentle, non-invasive and based entirely on what you already see at home, so there's no testing pressure on your child. Whether your child should have one depends on your concerns and age, and a Pinnacle clinician can confirm if it's the right fit.

What a CDI involves

There are no needles, no scary rooms and no pass-or-fail for your child. Instead:

• You're the expert. You tick off the words your child understands and says, and the gestures they use — pointing, waving, pretend play — from a structured list.
• It fits your child's age. One form focuses on Words & Gestures for younger babies and toddlers; another covers Words & Sentences as language grows.
• It takes 20–40 minutes and can be revisited over time to show how vocabulary is expanding.
• It's a snapshot, not a label. It gives the clinician a rich picture of your child's communication to combine with other observations.

Because it draws on everyday moments rather than a one-off test, the CDI often captures words your child uses with you that they might not show a stranger.

When it helps — and when to ask

A CDI is most useful if you've noticed your child is slower to babble, say first words, or combine words, or if you simply want a clear baseline. It is one piece of a fuller developmental check, not a diagnosis on its own. If your child has lost words they once had, isn't responding to their name, or you have any worry, bring it to a clinician promptly rather than waiting.

The Pinnacle way

A clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre, under the care of a qualified clinician — never from a form or an online figure. Our clinicians use parent-report tools like the CDI alongside a clinician-administered structured assessment to understand your child's whole communication picture, then turn it into practical speech therapy you can use at home. Backed by 2.5 billion+ data points and 25 million+ therapy sessions across 70+ centres, we make small gains visible. You can read how our measure works here: what the AbilityScore is and how it's calculated.

Trusted sources

ASHA guidance on early language assessment and parent-report measures; CDC and HealthyChildren (AAP) milestones for early communication and vocabulary; WHO frameworks for developmental language difficulties.

Next step — Not sure if a CDI is right for your child? Book an assessment with a Pinnacle clinician and get a clear, reassuring plan.

This is general information, not a diagnosis — individual assessment and diagnosis require an appropriately qualified healthcare professional.