Frequency lists are ranked inventories of words derived from corpora, ordered by how often they occur. They are foundational tools for vocabulary selection, materials grading, and measuring text difficulty in ELT.
Michael West's GSL was the first major frequency list for ELT, containing approximately 2,000 headwords selected from a 2.5–5 million word corpus. It provided ~84% coverage of general English text and remained the standard reference for over 50 years. Its limitations: the corpus was small by modern standards, drawn primarily from written British English, and the list has not been updated to reflect vocabulary change.
The NGSL modernised West's work using a 273-million-word subsection of the Cambridge English Corpus. It contains 2,809 lemmas (~2,368 word families) and provides ~90% coverage of general English, a significant improvement over the original GSL's 84%. The NGSL is freely available and regularly updated (most recent revision 2023).
Paul Nation created frequency lists in 1,000-word-family bands from the combined British National Corpus and Corpus of Contemporary American English. These lists underpin the Vocabulary Size Test and much vocabulary research. They cover 25 frequency levels (1K–25K).
Averil Coxhead's Academic Word List contains 570 word families not in the GSL's first 2,000 but frequent across academic disciplines. It covers approximately 10% of academic text.
The NAWL complements the NGSL, containing 963 word families that provide approximately 92% cumulative coverage of academic text when combined with the NGSL.
| Application | How frequency lists help |
|---|---|
| Vocabulary selection | Determine which words to teach at each level |
| Materials grading | Assess whether a text is level-appropriate |
| Test development | Ensure items target appropriate frequency bands |
| Learner profiling | Estimate vocabulary size against frequency benchmarks |
| Curriculum design | Sequence vocabulary instruction from high to low frequency |
Frequency lists are powerful but imperfect:
Despite these caveats, frequency data remains the most principled basis for vocabulary selection in language teaching.