Brown's Stages of Syntactic and Morphological Development

Typical expressive language development

"Brown's Stages" were identified by Roger Brown 1925-1997 and described in his classic book (Brown,1973).

The stages provide a framework within which to understand and predict the path that normal expressive language development usually takes, in terms of morphology and syntax (defined below).

They are used extensively by speech-language pathologists /speech and language therapists when they perform a structural analysis of a sample of a child's spoken language.

A structural analysis does not include a measure of a child's development in the area of the clarity of pronunciation of speech sounds. Such an analysis is done in addition to a structural analysis, and comprises, among other components, a phonetic assessment of the speech sounds a child can produce, and a phonological assessment of the way those sounds are organised into speech patterns.


In Linguistics, morphology is the branch of grammar devoted to the study of the structure or forms of words, primarily through the use of the morpheme construct. It is traditionally distinguished from syntax.


In Linguistics, syntax is a traditional term for the study the rules governing the combination of words to form sentences. It is distinguished from morphology, which is the study of word structure.


A morpheme is a unit of meaning. It does not necessarily relate to the "word count" or "syllable count" of an utterance. Here is an example of the way morphemes are counted in the words happy, unhappy, unhappily, and unhappiest, and the sentence 'He meets the unhappiest boys:

happy 'Happy’ is ONE WORD, it has TWO SYLLABLES (ha-ppy), and because it contains only one unit of meaning it is ONE MORPHEME.

unhappy If you add another unit of meaning, such as ‘un’, to make 'happy' into  ‘unhappy’ you still have ONE WORD, but THREE SYLLABLES (‘un-ha-ppy’) and TWO MORPHEMES (‘un’ and ‘happy’).

unhappily 'Unhappily' is ONE WORD, FOUR SYLLABLES (un-happ-i-ly), and THREE MORPHEMES ('un', 'happy' and 'ly').

unhappiest' Unhappiest' is also ONE WORD, FOUR SYLLABLES, and THREE MORPHEMES.

"He meets the unhappiest boys" is 1-sentence, it has 5-words, and 8-syllables, and it contains nine morphemes:

He meet s the un happi est boy s.
1 2 3 4 5 6 7 8 9
"The girl's mother slowly filled the bucket with water" is 1-sentence, it has 9-words, and 13-syllables, and it contains twelve morphemes.
The girl s mother slow ly fill ed the bucket with water.
1 2 3 4 5 6 7 8 9 10 11 12

Stage I Sentence Types


Operations of Reference



  Nomination that car That's a car.
  Recurrence more juice There is more juice.
  Negation - denial no wee wee I didn't do a wee wee.
  Negation - rejection no more I don't want more.
  Negation - non-existence birdie go The bird has gone.

Semantic Relations



  Action + Agent daddy kiss Daddy is kissing.
  Action + Object push truck Pushing the truck.
  Agent + Object man hat The man (wears) a hat.
  Action + Locative in bath I am in the bath.
  Entity + Locative dolly bed The dolly is on the bed.
  Possessor + Possession (object) Kim car Kim's car.
  Entity + Attributive water hot The water is hot.
  Demonstrative + Entity that train Not this train.

Brown's Stage I

Between 15 and 30 months, children are expected to have MLUm's (mean length of utterance measured in morphemes) of about 1.75 morphemes. Their MLUm’s gradually increase as they acquire more language.

In Stage I, just after they have built up a 50 to 60 word vocabulary, children acquire the ability to produce the Stage I sentence types, outlined below. The column headed 'intent' (short for 'communicative intent') includes examples of what the child might have said if they were mature enough to talk in full sentences.

Brown's Stages I to IV

As children's MLUm increases their capacity to learn and use grammatical structures of greater complexity increases. They move from Stage I into Stage II, where they learn to use "-ing" endings on verbs, "in", "on", and "-s" plurals. They then proceed to Stages III and IV.

  Age in
MLUm Range Morphological Structure Examples

Stage I   15-30 1.75 1.5-2.0 Stage 1 Sentence Types (see above)

Stage II   28-36 2.25 2.0-2.5    
1         present progressive it going (-ing verbs)
2         in in box
3         on on box
4         -s plurals my cars (regular plural)

Stage III   36-42 2.75 2.5-3.0    
5         irregular past tense me fell down
6         's posessive man's book

        uncontractible copula (the full form of the verb to be when it is the only verb in a sentence) Is it Alison?


Stage IV   40-46 3.5 3.0-3.7    
8         articles a book, the ball
9         regular past tense she jumped
        third person regular present tense puppy brings it

Stage V   42-52+ 4.0 3.704.5  
11         3rd person irregular he does, she has

        Uncontractible auxiliary (the full form of the verb 'to be' when it is an auxiliary verb in a sentence) Are they swimming?


        Contractible copula (the shortened form of the verb 'to be' when it is the only verb in a sentence She's ready.
They're here.


        Contractible auxiliary (the shortened form of the verb 'to be' when it is an auxiliary verb in a sentence) They're coming.
He's going.



Brown, R. (1973). A first language: The early stages. London: George Allen & Unwin.


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