Research shows that we need to know about 95% of the words in a text in order to understand it clearly. Using the multi-billion-word Cambridge English Corpus, a unique lexical syllabus has been created containing the most important words for second language learners of English. This syllabus comprises two word lists: a New General Service List (NGSL), a list of approximately 2,800 words; and a New Academic Word List (NAWL), a list of approximately 1,000 words which are especially useful for students who want to read academic texts in English. Together, these 3,800 words allow learners to understand 95% of most English texts; these are nearly all the words learners will ever need (not bad if you consider there are more than 600,000 words in English!).

In each level of In Focus, 120 of these words are taught in depth (10 per unit). In levels 1 and 2, these words are taken from the NGSL, while in level 3 they are taken from the NAWL. Students can use the online tools developed especially for In Focus to learn the remainder of the 3,800 words.