CHAT Format Overview

Status: Reference Last updated: 2026-05-11 21:51 EDT

CHAT (Codes for the Human Analysis of Transcripts) is a standardized transcription format for spoken language data, developed by MacWhinney as part of the CHILDES and TalkBank projects. It is the most widely used format in child language research and conversational analysis.

File Anatomy

Every CHAT file follows this structure:

@UTF8
@Begin
@Languages:	eng
@Participants:	CHI Target_Child, MOT Mother
@ID:	eng|corpus|CHI|2;6.||||Target_Child|||
@ID:	eng|corpus|MOT|||||Mother|||
*MOT:	what do you want ?
%mor:	ADV|what AUX|do PRON|you VERB|want ?
%gra:	1|4|LINK 2|4|AUX 3|4|SUBJ 4|0|ROOT 5|4|PUNCT
*CHI:	I want cookie .
%mor:	PRON|I VERB|want NOUN|cookie .
%gra:	1|2|SUBJ 2|0|ROOT 3|2|OBJ 4|2|PUNCT
@End

A CHAT file consists of:

1. @UTF8: required first line, declares UTF-8 encoding
2. @Begin: marks the start of the transcript
3. Headers: lines starting with @ that provide metadata (participants, languages, IDs, etc.)
4. Utterances: blocks consisting of:
   • A main tier (line starting with *SPEAKER:) containing the transcribed speech
   • Zero or more dependent tiers (lines starting with %tier:) containing annotations
5. @End: marks the end of the transcript

Key Conventions

• Tab separation: a tab character separates the tier prefix from its content (e.g., *CHI:⟶content)
• Terminators: every utterance ends with a terminator (., ?, !, or special forms like +...)
• Line continuation: long lines wrap with a tab at the start of continuation lines
• Speaker codes: short identifiers; the validator accepts up to seven characters from A-Z, 0-9, _, -, '; three uppercase letters is the convention (e.g., CHI, MOT, FAT, INV)
• Media linking: timestamps link transcripts to audio/video via bullet markers

CHAT vs Other Formats

References

• CHAT Manual: the canonical reference
• TalkBank: the data repository