This study investigates the percentage coverage of text needed for unassisted reading for pleasure, where learners can read without interrupting to look up words. The study examines the effect of three densities of unknown vocabulary (80%, 90%, and 95%) on two measures of reading comprehension: a multiple-choice test and a cued written recall test. The results show that with 80% coverage, none of the learners achieved adequate comprehension. With 90% and 95% coverage, some learners gained adequate comprehension but most did not. A regression analysis revealed a predictable relationship between the density of unknown words and comprehension. The study concludes that around 98% coverage of vocabulary is necessary for learners to gain unassisted comprehension of a fiction text. The findings support the idea that vocabulary knowledge is crucial for reading comprehension, but other factors such as background knowledge and reading skills also play significant roles. The study provides practical implications for teachers in guiding learners in choosing appropriate texts for extensive reading.This study investigates the percentage coverage of text needed for unassisted reading for pleasure, where learners can read without interrupting to look up words. The study examines the effect of three densities of unknown vocabulary (80%, 90%, and 95%) on two measures of reading comprehension: a multiple-choice test and a cued written recall test. The results show that with 80% coverage, none of the learners achieved adequate comprehension. With 90% and 95% coverage, some learners gained adequate comprehension but most did not. A regression analysis revealed a predictable relationship between the density of unknown words and comprehension. The study concludes that around 98% coverage of vocabulary is necessary for learners to gain unassisted comprehension of a fiction text. The findings support the idea that vocabulary knowledge is crucial for reading comprehension, but other factors such as background knowledge and reading skills also play significant roles. The study provides practical implications for teachers in guiding learners in choosing appropriate texts for extensive reading.