The purpose of this study is to show how retelling activities can be used to enhance Japanese high school students’ English proficiency. As a graduate student. the author participated in a ２-year teaching practicum at a public high school in Shimane Prefecture. The first-year research showed that retelling activities can provide students with valuable opportunities to practice speaking in their own words. Therefore, in the following year, experimental instruction was designed and given to two classes, and its effects were evaluated relative to a control group in terms of the amount of students’ utterances in retelling tasks. The results show that a) retelling activities increased the number of words students speak for １ min (but n. s.), and b) interactive instruction can be used to teach implicit retelling skills.