# What is the MacArthur–Bates Communicative Development Inventories (CDI)?

Canonical: https://pinnacleblooms.org/ask/what-is-the-macarthur-bates-communicative-development-inventories-cdi-and-what-does-it-assess
Publisher: Pinnacle Blooms Network / Bharath Healthcare Laboratories Private Limited

The MacArthur–Bates Communicative Development Inventories (CDI) are parent-report questionnaires that measure a young child's early communication — typically from around 8 months to 3 years. Because parents complete them from everyday life, they capture real-world skills: words understood, words said, gestures, and early word combinations. The CDI is a screening and research tool, not a diagnosis; a low score is an invitation to look more closely with a professional.

*A simple checklist a parent fills in — turning what you already notice about your child's words and gestures into a clear picture of early communication.*

## In short
The **MacArthur–Bates Communicative Development Inventories (CDI)** are a well-established set of parent-report questionnaires that measure a young child's early language and communication. Because you, the parent, complete them based on what your child does in everyday life, the CDI captures real-world communication rather than how a child behaves in an unfamiliar room. They are widely used from around 8 months to 3 years to track words a child understands, words they say, gestures, and the first steps of sentence-building.

## What the CDI assesses
The CDI comes in forms suited to different ages, and together they look at several threads of early communication:

- **Words understood (receptive vocabulary)** — the words your child seems to recognise, even before they can say them.
- **Words said (expressive vocabulary)** — the words your child actually uses.
- **Gestures and actions** — pointing, waving, showing, and play gestures that are the foundation of communication before speech.
- **Early grammar** — for older toddlers, how words begin to combine into short phrases and sentences.

Because parents see their child across many natural moments — meals, play, bath time — the CDI is considered a reliable, low-stress way to gather rich information. It is a **screening and research-supported tool**, not a stand-alone diagnosis. A score below the typical range is best understood as an invitation to look more closely with a professional, not a verdict.

## When it helps
The CDI is especially useful when a parent or clinician wants to understand a late talker, track progress over time, or add a parent's everyday observations to a fuller developmental review. It works alongside — never instead of — a clinician's direct assessment of how a child listens, plays and communicates.

## The Pinnacle way
This is general information, not a diagnosis — a clinical [AbilityScore®](/ask/what-is-the-abilityscore-and-how-is-it-calculated) and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care, never from a single form. Our team may use parent-report tools like the [CDI](/cdi) together with structured observation, then shape an individualised plan that can draw on [speech therapy](/speech-therapy) where it helps your child flourish.

## Trusted sources
ASHA guidance on early language development and parent-report measures; CDC developmental milestone resources on communication; the WHO Nurturing Care Framework on early childhood communication and learning.

**Next step —** If you'd like to understand your child's early words and gestures, book a developmental review where a clinician can combine your everyday observations with a careful look at how your child communicates.

## Sources
- ASHA — early speech and language development: https://www.asha.org/public/speech/development/
- CDC — developmental milestones: https://www.cdc.gov/child-development
- WHO Nurturing Care Framework: https://nurturing-care.org/

## Connected topics and perspectives
- Assessments: https://pinnacleblooms.org/ask/assessments
- Parent: https://pinnacleblooms.org/ask/lens/stakeholder/parent
- Definition: https://pinnacleblooms.org/ask/lens/intent/definition
- Measure: https://pinnacleblooms.org/ask/lens/lifecycle/measure
- Screen: https://pinnacleblooms.org/ask/lens/route/screen
- Early Clarity: https://pinnacleblooms.org/ask/lens/empowerment/early_clarity

## Related question paths

### Understand the subject
- At What Age Is the CDI Used for a Child?: https://pinnacleblooms.org/ask/at-what-age-is-the-cdi-developmental-assessment-used-for-a-child

### Understand assessment
- Should My Child Have a CDI Assessment?: https://pinnacleblooms.org/ask/should-my-child-have-a-cdi-assessment-and-what-does-it-involve
- When the CDI Is Indicated: Strengths and Limits in Early Childhood: https://pinnacleblooms.org/ask/when-is-the-cdi-indicated-and-what-are-its-strengths-and-limits-in-early-childhood
- How does the CDI compare with the AbilityScore developmental assessment?: https://pinnacleblooms.org/ask/how-does-the-cdi-compare-with-the-abilityscore-developmental-assessment
- Standardised instruments for the Communication domain (ICF d3): https://pinnacleblooms.org/ask/which-standardised-instruments-assess-the-communication-developmental-domain-in-young-children
- How is developmental age assessed for the Communication domain?: https://pinnacleblooms.org/ask/how-is-developmental-age-assessed-for-the-communication-domain