The aim of this study is to investigate the effects of extensive reading (ER) and shadowing on performance on reading comprehension tests. This study addressed the following research questions: (a) Can extensive reading improve students’ reading comprehension? and (b) can shadowing enhance the effects of extensive reading? The participants in the study were 89 Japanese university students majoring in human science. Based on two experimental groups and two control groups, we examined the relationships and interactions of the two variables (ER and shadowing) over a one-year treatment (two semesters), using ANOVA. Three reading comprehension tests, a pretest, posttest 1 (after the first semester), and posttest 2 (after the one-year treatment), were administered. The results indicated that there was no statistically significant difference among groups, but a significant difference was found between the three test scores. Results are also considered in terms of an increased understanding of shadowing, and implications for curricula and classroom applications are discussed
