This study investigates how the implementation of extensive reading and reading strategy training in a Content and Language Integrated Learning (CLIL) program fostered undergraduate students' reading comprehension and strategy use. The research employed a quasi-experimental design, with 60 Japanese students being divided into control and experimental groups. They were tested with pre- and post-reading comprehension tasks and assigned to do pre- and post-standardized reading strategy questionnaires. The results reveal that the experimental group, who received reading strategy instruction and engaged in extensive reading, exhibited an increase in top-down reading strategy use. Although the intervention of reading strategy training and extensive reading in CLIL had a positive effect on reading comprehension, the impact was found to be non-significant when compared to traditional reading instruction. The findings have implications for CLIL teachers and curriculum designers, as they shed the light on steps to incorporate extensive reading and reading strategies in CLIL programs.