Print or Save as PDF
Karla K. McGregor, Ph.D.
Boys Town National Research Hospital

The school years are a period of rapid vocabulary growth. Although the average student learns about 1000 new root words per year, every child is different. For example, at the end of second grade, some children will know roughly 8,000 words but others will know only 4,000.

Children with small vocabularies are at a disadvantage when learning to read. The correlation between vocabulary size and reading comprehension is strong, and vocabulary size predicts growth in reading too. Teaching children the meanings of unfamiliar vocabulary in a text improves their comprehension of the text and helps weaker readers to figure out the meanings of other words in that text.

Spoken vocabulary is the lexicon of words a person uses and understands while speaking—is a critical foundation for learning to read.

Stronger spoken vocabulary yields:

  • Better reading comprehension
  • Better phonemic awareness
  • Better decoding of words with unfamiliar printed forms
  • Better word recognition

Some, but not all, children with DLD have small vocabularies and this is part of the reason that they also have a hard time with reading. Interventions that help children with DLD to boost their vocabulary might, in turn, improve their reading. Tunmer and Chapman write, “…prevention programs for children at risk of reading failure should focus on improving these children’s oral language skills, especially vocabulary knowledge, as well as their phonological and alphabetic coding skills.” –2012, p. 464.

The National Reading Panel (2000) recommended the following:

  • Vocabulary should be taught both directly and indirectly.
  • Repetition and multiple exposures to vocabulary words are important.
  • Learning vocabulary in rich contexts is valuable.
  • Vocabulary learning should entail active engagement in learning tasks.

How do I know if my child needs help with vocabulary?

Naturally, younger children tend to have smaller vocabularies than older children. Also, depending on their age, even children with small vocabularies may know thousands of words. This makes it difficult to judge whether a child is trailing behind in vocabulary development. There are some warning signs though. A child who has a small vocabulary might:

  • Understand conversations about the “here and now” but have more difficulty when talking about things that can’t be seen
  • Understand concrete words like “table” but have more difficulty with verbs like “pull” and abstract words like “thought”
  • Overuse vague words like “thing” or “stuff”
  • Abandon sentences, seemingly because of trouble finding the right word
  • Have difficulty with language heavy school assignments

We don’t have to wait for a child to fail at reading before we take action. If you are concerned about your child’s vocabulary development, talk to your speech-language pathologist. If your child is not already seeing a speech-language pathologist, ask your school for an evaluation.


Anglin, J. M., Miller, G. A., & Wakefield, P. C. (1993). Vocabulary development: A morphological analysis. Monographs of the society for research in child development, i-186.

Biemiller, A., & Slonim, N. (2001). Estimating root word vocabulary growth in normative and advantaged populations: Evidence for a common sequence of vocabulary acquisition. Journal of educational psychology, 93(3), 498-520.

Catts, H. W., Fey, M. E., Zhang, X., & Tomblin, J. B. (1999). Language basis of reading and reading disabilities: Evidence from a longitudinal investigation. Scientific studies of reading, 3(4), 331-361.

Clarke, P. J., Snowling, M. J., Truelove, E., & Hulme, C. (2010). Ameliorating children's reading-comprehension difficulties: A randomized controlled trial. Psychological Science, 21(8), 1106-1116.

Duff, D. M. (2015). Lexical semantic richness: effect on reading comprehension and on readers' hypotheses about the meanings of novel words. The University of Iowa.

Ehri, Linnea C. "How Children Learn to Read Words." The Oxford handbook of reading (2015): 293.

Nation, K., & Snowling, M. J. (1998). Semantic processing and the development of word-recognition skills: Evidence from children with reading comprehension difficulties. Journal of memory and language, 39(1), 85-101.

National Reading Panel (US), National Institute of Child Health, & Human Development (US). (2000). Report of the national reading panel: Teaching children to read: An evidence-based assessment of the scientific research literature on reading and its implications for reading instruction: Reports of the subgroups. National Institute of Child Health and Human Development, National Institutes of Health.

Ouellette, G. P. (2006). What's meaning got to do with it: The role of vocabulary in word reading and reading comprehension. Journal of educational psychology, 98(3), 554.

Tunmer, W. E., & Chapman, J. W. (2012). The simple view of reading redux: Vocabulary knowledge and the independent components hypothesis. Journal of learning disabilities, 45(5), 453-466.

Walley, A. C., Metsala, J. L., & Garlock, V. M. (2003). Spoken vocabulary growth: Its role in the development of phoneme awareness and early reading ability. Reading and Writing, 16(1), 5-20.