A systematic review of the research on vocabulary instruction that impacts text comprehension

Wright, T.S., & Cervetti, G.N. (2017). A systematic review of the research on vocabulary instruction that impacts text comprehension. Reading Research Quarterly, 52(2), 203-226.


This article gets at what we already know, and what we still don’t know, about what effective vocabulary instruction is. It is useful as a refresher on current theory and practice in vocabulary instruction. It also suggests directions for researchers interested in expanding what we know about this basic component of literacy instruction.

So, what do we already know? First, the relationship between vocabulary knowledge and text has long been established, and there are no debates about the importance of that relationship to learners’ overall reading achievement. Wright and Cervetti begin with a concise summary of the hypotheses researchers have proposed to describe the nature of that relationship. This should be familiar territory to anyone who has read much on vocabulary development, but the refresher provided here is valuable.

Next, Wright and Cervetti provide a review of 36 studies that examined the effectiveness of various vocabulary interventions on students’ text comprehension. Most of the study interventions involved direct teaching of specific vocabulary words that then occurred in the passages that students read. It seems clear that when specific words are taught before or during instruction, students comprehend text passages with those words in them better. It seems that almost any kind of specific vocabulary instruction, even if it is brief, is better than no vocabulary instruction at all. However, the effects seem to be limited to the comprehension of the specific passage being read. Researchers have not yet been able to show that instruction focused on specific vocabulary words transfers across other texts. A few studies have been done on instruction that focuses on vocabulary strategies, but so far there has not been much convincing evidence that such strategy instruction leads to better text comprehension in general.

Another pattern that emerged in this review is that active processing of words is probably better than more “surface-level” processing. For example, merely providing definitions and contexts is less effective than really having students work with words; active processing might involve classifying, comparing, discussing, mapping, and other activities that require “active mental manipulation of word meanings” (p. 220). Research seems to suggest that active processing helps, but we know less about how much active processing is helpful, and exactly what kinds of activities best help students comprehend texts.

One of the most cautionary findings for me in the article was that there is no evidence to support the teaching of one or two general strategies for deciphering unknown words. For example, just teaching students to use context clues did not seem to promote general comprehension of texts. The authors suggest that perhaps more long-term instruction is needed for strategy instruction to work well. Maybe instruction focusing on multiple strategies, with lots of deep processing of words, would produce improved comprehension. That kind of vocabulary instruction would require a heavy investment of time, both to implement the intervention and to conduct the longitudinal studies that Wright and Cervetti recommend to determine the effectiveness of the intervention.

Clearly, there is much more to be learned about what effective vocabulary instruction should look like in the classroom. A wide variety of approaches is represented across the 36 studies reviewed here. Some of the top researchers in this area have proposed intensive procedures, some of which represent a heavy time investment in classrooms. As the authors point out, instructional time is a valuable and scarce resource in the classroom. Without evidence that an intensive vocabulary intervention actually has strong benefits for students’ comprehension, it is difficult to justify spending valuable classroom time on it. An intervention that requires extensive time, energy, and other resources is less likely to be implemented, and if it is, it will have to clearly lead to improved student learning.