Abstract
The purpose of this study is to clarify indications from my previous studies (Yashima, 2000, 2001) showing that a 1:40 ratio of unknown to known words was efficacious to guess word meanings successfully from contextual clues. The study examines differences in success rates among different senior high schools and differences in the use of contextual clue types. Differences in success rates are also examined according to students' vocabulary size. In addition, the study examines the influence of genres on mean success rates. Findings reveal significant differences in the mean success rates among schools and between the different genres used in the experiment. Also there were significant differences in students' use of local and global contextual clues. The study concludes that students with vocabularies exceeding 3,000 words can successfully guess around 60 percent of unknown words.
