Before you read this, here is a reminder of my site with links to research papers and videos about second language learning and teaching: informedlanguageteacher.com
I originally published a post in 2018 which summarised Chapter 16 of the Routledge Handbook of Instructed Second Language Acquisition (2017), edited by Loewen and Sato. With the aid of ChatGPT I have kept the content and structure of the original post and added a few observations from research published since then. These are marked in bold.
Background
The authors of the 2017 chapter begin by outlining the clear importance of vocabulary knowledge in language acquisition, stating that it's a key predictor of overall language proficiency (e.g. Alderson, 2007). Students often say that their lack of vocabulary is the main reason for their difficulty understanding and using the language (e.g. Nation, 2012). Historically vocabulary has been neglected when compared to grammar, notably in the grammar-translation and audio-lingual traditions as well as communicative language teaching.
(My note: this is also true, to an extent, of the oral-situational approach which I was trained in, where most vocabulary is learned incidentally as part of question-answer sequences or textual study. I began my career with a strong antipathy to formal vocabulary learning and have not changed my mind.)
Vocabulary back on the agenda
In 1990 Paul Nation was the main impetus behind a new focus on vocabulary with his book Teaching and Learning Vocabulary. This book offered a principled approach, notably arguing that the study of vocabulary frequency is the best way of organising a course.
Vocabulary acquisition now has a central role in the field of Instructed Second Language Acquisition (ISLA). Nation (2013) estimated that over 30% of all the research on vocabulary had been published in the previous 11 years.
Empirical evidence
The mental lexicon
It is unclear how vocabulary is stored and processed in the mental lexicon, but vocabulary knowledge is not just about knowing words. It's about having all sorts of knowledge about words and having connections between them. Learning one item has an effect on learning others (Meara & Wolter, 2004). Evidence shows that L2 vocabulary learning is not just about integrating new knowledge into existing L1 knowledge, but establishing new connections through exposure to words in varying contexts. In short, the more contacts you have with a word, in varying situations, the better you will remember it.
Knowing a word
The authors summarise Nation's (2013) framework regarding what 'knowing' a word means. This includes the word's form (e.g. spoken, written, word parts), its meaning (e.g. what it refers to and its associations) and its use (e.g. its grammatical functions, collocations and restrictions on use).
Word knowledge includes both breadth and depth (Anderson & Freeman, 1981). These can interact, e.g. the more words you know, the more examples of word parts like prefixes and suffixes you will know – so breadth develops depth. Breadth usually develops before depth, meaning that beginner and intermediate students have more difficulty putting sentences together.
Receptive and productive knowledge
In addition, the distinction is made between receptive and productive knowledge. The former unsurprisingly develops first. One study (Nemati, 2010) found that receptive knowledge may be five times greater than productive. So students typically recognise words but cannot recall and use them.
Research cited in the chapter suggests that learners require anything between 2,000 and 7,000 word families to hold everyday conversations. To understand spoken narratives you need to understand around 95% of the words, e.g. van Zeeland and Schmitt (2013).
(My note: as is often pointed out, when setting listening or reading texts it is recommended that at least 95% of the words already be known to students. But be wary of this percentage. One obvious issue is that precise figures do not take account of lexical phrases (chunks) or well-known formulaic phrases, of which there are many. In addition, words in texts can be glossed and many cognates may or may not be recognised by learners.
A gradual process
The authors point out that vocabulary acquisition is an incremental process. Different aspects of word knowledge are learned at different rates and more research is needed on this. Some aspects seem to be learned in order, e.g. Schmitt (1998) found in a study of 11 words that spelling, derivative information, associations and polysemy were acquired in sequence. Webb (2007) found that aspects of word knowledge were acquired in parallel but at different rates.
In addition, aspects of word knowledge are picked up gradually, along a continuum ranging from zero knowledge to precise knowledge (e.g. Henriksen, 1999). Finally, receptive mastery precedes productive mastery. One researcher (Fitzpatrick, 2012) found that aspects of vocabulary knowledge can regress.
(My note: all this sounds like confirmation of common sense to me. But common sense is not good enough in research, of course!)
Formulaic language
Formulaic language consists of idioms, lexical chunks and collocations. In English it has been calculated that these occupy between a third and a half of all conversation (Conklin & Schmitt, 2012). The writers naturally conclude that both isolated words and formulaic language should form part of vocabulary teaching.
Update (2026): A meta-analysis by Yi and Zhong (2024) adds further support to the importance of chunks. It found that familiar multiword sequences generally enjoy a processing advantage over unfamiliar word combinations, for both first- and second-language users. This doesn't tell us precisely how to teach chunks, but reinforces the argument for teaching useful phrases alongside individual words. (See my further note below!)
Incidental learning
This means picking up words when vocabulary acquisition is not the main goal. The learner's attention is primarily on meaning rather than deliberately memorising vocabulary (e.g. Hulstijn, 2001). Lots of learning occurs this way, although uptake can be slower and more uneven. This is because the number of exposures needed to learn incidentally can be high. As a rule of thumb, 8–10 exposures have sometimes been suggested for students to get words right in tests. Other researchers have come up with lower figures.
(My note: there must surely be some huge caveats here, notably how the vocabulary is tested and how able each student is.)
Research suggests that incidental learning through listening may require more exposures (e.g. van Zeeland and Schmitt, 2013). Nevertheless, listening tasks are a good source of incidental vocabulary learning. In both listening and reading high-frequency words are more quickly acquired than low-frequency words.
Update (2026): A substantial meta-analysis by Webb, Uchihara and Yanagisawa (2023), covering 24 studies, found that learners typically acquired between 9% and 18% of target words on immediate tests following meaning-focused activities. The figures varied according to the mode of input, learners and assessment methods. This confirms that incidental learning is valuable, but also reminds us that simply encountering new words does not guarantee learning them.
Research into video viewing has also developed. Kurokawa, Hein and Uchihara (2025) found that watching videos with captions in the target language produced greater incidental vocabulary gains than watching without captions. This provides another reason to consider captioned video as a useful source of vocabulary input.
Intentional learning
This means deliberate attempts to learn new words. This can be through direct instruction such as call-and-response flashcard work, matching tasks, gap-fills, or through personalised learning from lists. As mentioned above, there is research to suggest that intentional learning is more efficient (e.g. Webb, 2007). Laufer and Rozovski-Roitblat (2011) found that intentional exercises (practising words out of context, synonym and antonym work, selecting the right meaning from options, writing words in sentences) led to better recall, both short- and long-term, than incidental approaches. Bilingual word lists and flashcards have been found to be useful. Meaning-focused output (e.g. writing new words in sentences) is also supported by research.
Other research suggests that the best approach is to combine intentional with incidental learning, where the latter reinforces the former.
(My note: many teachers will find this all uncontroversial since they do much or all of this already.)
Update (2026): Webb, Yanagisawa and Uchihara (2020) reviewed 22 studies of intentional vocabulary-learning activities, including flashcards, word lists, writing and gap-fills. They found substantial immediate learning gains, although these declined on delayed tests and there was considerable variation between activities.
Another meta-analysis, by Yanagisawa and Webb (2021), lends support to the idea that vocabulary tasks are more effective when learners have to engage meaningfully with words. In particular, activities requiring learners to evaluate how words are used were associated with greater learning. This suggests that we should consider not just how many times a word is encountered, but what learners actually do with it.
Multiple encounters
You'll be unsurprised to learn that the authors provide research evidence for the value of recycling words. Multiple encounters lead to greater all-round knowledge of a word, both breadth and depth of knowledge (see above).
Update (2026): Uchihara, Webb and Yanagisawa (2019) confirmed a positive relationship between repeated encounters and incidental vocabulary learning, but also found that the strength of this relationship depended on factors such as age, previous vocabulary knowledge, spacing and learner engagement. There is no magic number of repetitions which guarantees learning. (My italics)
A further meta-analysis by Kim and Webb (2022) found that spaced practice was generally more effective than massed practice for second language learning, particularly for longer-term retention. So a little practice spread over several lessons is likely to be more productive than cramming everything into one session.
What does this all mean for the teacher?
- Vocabulary acquisition requires multiple encounters with words and chunks, and some teachers may need to spend more time on this in a planned way. Vocabulary should be prioritised (ahead of grammar?). (My note: this was pointed out by the TSC Review of MFL Pedagogy, 2016. I am also reminded of Wilkins's quotation about how you can say something with vocabulary alone, but nothing with grammar alone.)
- Incidental picking up of vocabulary is not enough, however important that may be. Specifically, the authors suggest:
- Provide rich and varied language experiences through the four skills, including independent work beyond the classroom, e.g. homework.
- Provide multiple encounters with words, compensating for any lack thereof in textbooks.
- Provide instruction of words using clear explanations, explicit methods and simple definitions, then make sure words are recycled in various contexts. Different words may require different teaching methods. (My note: e.g. flashcards for simple concrete nouns, collocations for adjectives.)
- Teach strategies for independent learning, e.g. explain how students can use morpheme clues, infer from context, use dictionaries and so on.
- Foster the active engagement of students in vocabulary learning – promote interest and involvement.
- Extensive reading and listening will help develop vocabulary. Graded readers are a good idea.
- For collocational knowledge and restrictions on use, massive exposure is needed – provide as much as possible at higher levels.
- Consider setting awkward words for learning before the class so that they are better understood when seen in context.
Update (2026): I would add two practical points in the light of more recent research. First, build spaced retrieval into schemes of work so that vocabulary is revisited over weeks and months, rather than just within a single unit. Second, aim for a mixture of deliberate learning, comprehension-based encounters and opportunities to retrieve and use vocabulary meaningfully. Repeated exposure matters, but the quality of engagement matters too.
Conclusion
As is uniformly the case in this handbook, the theoretical, research aspects are far better dealt with than the teacher tips. This is true of the end of this chapter, where the authors quote from Nation's (2007) four strands of successful vocabulary teaching. Nation recommended that time be equally shared between the four strands. Good general advice, but fairly limited on specific classroom tasks.
(My note: time devoted to tasks must also depend on the nature of the assessment regime students are subject to, e.g. GCSE in England allows too little time for extensive reading and listening and, arguably, much incidental learning. I would also add that my impression of reading Nation and, for example, Joe Barcroft, is that they lean more towards incidental learning than the authors of this chapter.)
So, Nation's general points:
a. Provide lots of meaning-focused input (reading and listening).
b. Provide opportunities for meaning-focused output (speaking and writing).
c. Include form-focused instruction – direct teaching of word forms, sounds, spellings, grammatical features, gender and so on.
d. Provide fluency-focused tasks, e.g. skimming and scanning, timed writing and speaking, speed reading.
Final update (2026): Seven or eight years on, I don't think the broad picture has changed dramatically. What we have is stronger evidence for the value of deliberate vocabulary learning, meaningful exposure, spaced practice and engagement with words in context. For classroom teachers, the challenge remains finding enough time for all these processes, particularly when curriculum time is limited. No single activity or technique is likely to do the whole job.
I remain convinced that the focus should be, as far as possible, on words in chunks rather than on isolated words. Learning words in isolation just does not not cover all the dimensions of words, is boring and transfers poorly to actual language comprehension and use. I would seriously implore teachers to consider this, whatever the power of tradtion!
References The original post was based on Chapter 16 of the Routledge Handbook of Instructed Second Language Acquisition (2017), edited by Loewen and Sato. The references cited before 2019 are taken from that chapter and my original notes.
Additional research cited in the 2026 updates:
Uchihara, T., Webb, S. & Yanagisawa, A. (2019). The effects of repetition on incidental vocabulary learning: A meta-analysis of correlational studies. Language Learning, 69(3), 559–599. https://doi.org/10.1111/lang.12343
Webb, S., Yanagisawa, A. & Uchihara, T. (2020). How effective are intentional vocabulary-learning activities? A meta-analysis. The Modern Language Journal, 104(4), 715–738. https://doi.org/10.1111/modl.12671
Yanagisawa, A. & Webb, S. (2021). To what extent does the involvement load hypothesis predict incidental L2 vocabulary learning? A meta-analysis. Language Learning, 71(2), 487–536. https://doi.org/10.1111/lang.12444
Kim, S. K. & Webb, S. (2022). The effects of spaced practice on second language learning: A meta-analysis. Language Learning, 72(1), 269–319. https://doi.org/10.1111/lang.12479
Webb, S., Uchihara, T. & Yanagisawa, A. (2023). How effective is second language incidental vocabulary learning? A meta-analysis. Language Teaching, 56(2), 161–180. https://doi.org/10.1017/S0261444822000507
Yi, W. & Zhong, Y. (2024). The processing advantage of multiword sequences: A meta-analysis. Studies in Second Language Acquisition, 46(2), 427–452.
Kurokawa, S., Hein, A. M. & Uchihara, T. (2025). Incidental vocabulary acquisition through captioned viewing: A meta-analysis. Language Learning, 75(4), 939–987. https://doi.org/10.1111/lang.12697
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