The purpose of this study is to improve teaching of English reading at the high school level by identifying the students’ challenges in reading English with a focus on text difficulty. As some studies have shown, high school English textbooks are likely to be beyond the students’ reading ability. Two investigations were conducted to understand high school students’ actual experience. First, high school students’ awareness of text difficulty was investigated. 77 high school students and 10 teachers were surveyed using a questionnaire that aimed to identify the readers’ assessment of text difficulty. The answers of 64 students and 10 teachers were analyzed and the results show that both students and teachers consider their textbook to be at the proper level, but that the students, especially poorer readers, identified only a fraction of what the teachers think can lead to difficulty in reading. Second, high school students’ reading processes were examined using texts of different difficulty levels in a qualitative study comprising observations and interviews of two students from different reading proficiency levels. The data show that the more-proficient student recognizes the difference in text difficulty and reads the text accordingly, while the less-proficient student hardly does.