Question 1

What are Brown's stages of language development?

Accepted Answer

Brown's stages are five developmental phases of early language identified by Roger Brown in his 1973 book A First Language: The Early Stages. Each stage corresponds to a range of Mean Length of Utterance (MLU) in morphemes and is characterised by the emergence of specific grammatical structures. Stage I starts at MLU 1.0 with single-word and two-word combinations; Stage V+ begins at MLU 4.5 with adult-like syntax and mastery of Brown's 14 grammatical morphemes.

Question 2

How do I use Brown's stages clinically?

Accepted Answer

Use Brown's stages as a developmental framework to describe where a child is in their early grammatical acquisition and what structures should emerge next. Compute the child's MLU-morphemes from a 50 to 100 utterance language sample, look up the matching stage, and target morphemes from the next stage as therapy goals. Brown's stages are descriptive, not normative on their own — pair them with SUGAR (Pavelko & Owens 2017) or Rice et al. (2010) age norms to decide whether a child's MLU is age-appropriate.

Question 3

What are Brown's 14 morphemes?

Accepted Answer

Brown identified 14 grammatical morphemes that typically developing children acquire in a predictable order between 18 and 48 months: present progressive -ing, preposition in, preposition on, regular plural -s, irregular past tense, possessive -s, uncontractible copula, articles (a, the), regular past -ed, regular third-person singular -s, irregular third-person singular, uncontractible auxiliary, contractible copula, and contractible auxiliary. Mastery is defined as correct use in 90% of obligatory contexts across three consecutive language samples.

Question 4

How are the age ranges in Brown's stages determined?

Accepted Answer

Brown's (1973) age ranges come from his longitudinal study of three children (Adam, Eve, and Sarah). They are approximate and should be interpreted as 'the age by which a typically developing child usually reaches this MLU range,' not as a hard cut-off. Later work by Miller and Chapman (1981), Rice et al. (2010), and Pavelko and Owens (2017) refined the age norms for MLU, but Brown's stages remain the standard descriptive framework for early grammatical development.

Question 5

Can I use Brown's stages with bilingual children?

Accepted Answer

Brown's stages were developed on monolingual English-speaking children. The MLU-to-stage mapping may not hold for bilingual children, who distribute their grammatical development across two languages. For Spanish-speaking children, the Spanish version of SUGAR and work by Restrepo and colleagues provide better age norms. Use Brown's stages cautiously with bilingual children and always collect language samples in both languages before drawing developmental conclusions.

Question 6

What happens above Stage V?

Accepted Answer

Stage V+ (sometimes called Post-V or Stage VI) covers MLU above 4.5 morphemes, typically from 47 months onward. At this point the child has mastered Brown's 14 grammatical morphemes and is producing adult-like syntax: coordinated clauses, embedded sentences, relative clauses, and complex verb forms. For school-age children, MLU becomes a less sensitive measure of grammatical development and clinicians shift to narrative-level metrics like Narrative Scoring Scheme (NSS), clausal density, and subordination index.

Brown's Stages Lookup

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What Are Brown's Stages?

How to Use This Tool

Brown's 14 Morphemes — Order of Acquisition

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Next Steps

MLU Calculator — compute MLU-morphemes from a transcript

SUGAR Norms Lookup — age-matched reference values

Lexical Diversity Calculator — TTR and NDW

PGU Calculator — percentage of grammatical utterances

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