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Morpheme #1 of 14Brown's Stage II19–28 months

Present Progressive -ing

Present progressive -ing is the first of Brown's 14 grammatical morphemes that English-speaking toddlers master, typically between 19 and 28 months of age.

At a glance

Acquisition order
#1 of 14 (Brown 1973)
Symbol / form
-ing
Brown's stage
II
Typical age of mastery
19–28 months

Mastery is defined as correct use in 90% of obligatory contexts across three consecutive language samples (Brown 1973). Individual variation is wide — these ranges describe typically developing English-speaking children and should be cross-referenced against the primary literature before clinical use.

What this morpheme is

Present progressive -ing is the verbal suffix that marks an ongoing action in English ("running", "eating", "sleeping"). Brown placed it first in his order of acquisition because it was the morpheme that reached 90% mastery earliest in his three longitudinal subjects (Adam, Eve, and Sarah). The morpheme is unusual within the 14 in that the auxiliary verb "is" or "are" is acquired separately and much later — toddlers in Stage II routinely produce "mommy running" without the auxiliary, and clinicians should not penalise the missing auxiliary when scoring the -ing inflection itself.

Acquisition trajectory

The trajectory is fast and remarkably stable across children. Toddlers move from no use of -ing in obligatory contexts at around 18 months to consistent use by 28 months in typical development. The morpheme appears earliest on highly familiar verbs of motion ("running", "walking", "going") before generalising to verbs of ingestion and play. Brown observed that -ing is rarely overgeneralised to stative verbs in the first wave of acquisition, which sets it apart from the regular past -ed marker that comes much later. Cross-linguistic note: in dialects of African American English the -ing morpheme is preserved in identical contexts as in mainstream American English, so its absence in a child speaker should not be attributed to dialect alone. Sporadic omission of -ing on a brand-new vocabulary verb is typical even after mastery has been demonstrated on familiar items, and clinicians should sample across at least 50 utterances before making a mastery judgement.

Examples in obligatory context

These are the kinds of child utterances a clinician would code as a correct production of -ing when scoring a language sample.

  • “Mommy running.”
  • “Doggie eating.”
  • “Baby sleeping.”
  • “Daddy reading book.”
  • “I painting the wall.”
  • “The car going fast.”

Common errors during the acquisition window

  • Bare stem on a familiar action verb: "mommy run" for "mommy is running"
  • Omission on a novel verb the child has only heard a handful of times
  • Substitution of a different aspectual form: "mommy runned" instead of "running"
  • Inconsistent application across the same verb in the same sample

Many of these errors are developmentally normal during the acquisition window. The clinical signal is persistence past the typical age of mastery, not the presence of any single error in early production.

Clinical relevance and scoring

Because present progressive -ing is the first morpheme to reach mastery, its absence in a 30-month-old who is producing two- and three-word combinations is an early grammar warning sign worth a referral. Once acquired, -ing is among the most reliably preserved morphemes in childhood DLD — children with DLD typically retain -ing while losing tense and agreement markers. That asymmetry is itself diagnostic: a school-age child who omits regular past -ed and third-person -s but uses -ing fluently is showing the classic Rice and Wexler tense-marking deficit. Score -ing in a 50-utterance sample by counting every obligatory context for present progressive (any "is/are X-ing" frame) and dividing the correct -ing productions by the obligatory total. Mastery is 90% across three consecutive samples per Brown.

“The first of the fourteen is also the most stubborn to lose. If a 4-year-old is dropping -ing on familiar verbs in connected play, you are not looking at an isolated grammar slip — pull a full language sample and check tense and agreement everywhere.”
The first morpheme is the last to fail

Free tools for scoring this morpheme

MLU Calculator

Paste a language sample and get Mean Length of Utterance in morphemes and words, total utterances, total morphemes, and the matching Brown's stage. Implements Brown (1973) morpheme counting rules and runs entirely in your browser.

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Brown's Stages Lookup

Interactive reference for Brown's (1973) five stages of grammatical development. Look up a stage by child age or MLU, see the MLU range, acquired morphemes, example utterances, and clinical milestones for each stage.

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Language Sample Worksheet

Free printable and fillable language sample analysis worksheet for speech-language pathologists. Five columns (utterance #, transcription, morpheme count, grammatical Y/N, notes), configurable row count up to 100 utterances, browser print produces a clean PDF, and an inline running summary tracks total utterances, total morphemes, and rolling MLU as you fill it in.

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Related morphemes

#2 · Stage II

Preposition "in"

The locative preposition "in" is the second of Brown's 14 morphemes, typically mastered between 27 and 30 months alongside its sibling "on".

#3 · Stage II

Preposition "on"

The locative preposition "on" is the third of Brown's 14 morphemes, mastered alongside "in" between 27 and 30 months in typical development.

#4 · Stage II

Regular Plural -s

Regular plural -s is the fourth of Brown's 14 morphemes, marking countable noun plurality and reaching mastery between 27 and 33 months.

References

  1. Brown, R. (1973). A First Language: The Early Stages. Harvard University Press, pp. 271–298.
  2. de Villiers, J. G., & de Villiers, P. A. (1973). A cross-sectional study of the acquisition of grammatical morphemes in child speech. Journal of Psycholinguistic Research, 2(3), 267–278.
  3. Rice, M. L., & Wexler, K. (1996). Toward tense as a clinical marker of specific language impairment in English-speaking children. JSLHR, 39(6), 1239–1257.