The purpose of this study is to explore changes in students’ interest levels in English reading practice with the intention of prompting self-regulated learning through stimulated recall procedures. Participants were students at a high school in Japan. They were asked to report their interests and reasons for having such interests through two to four scenes of each lesson. Data were examined as follows. First, we aggregated the data pertaining to students’ interests and considered the overall tendency of the lesson. Next, we selected lessons where students’ interests decreased and considered the factors responsible for the decline. Findings revealed the following points. First, there are five factors that influence the students’ interests. Second, the following factors are crucial for encouraging students’ active and spontaneous learning of the lessons: strategies with clear goals, ingenious ways of developing lessons and students’ learning during the instruction of the strategies, designing materials that stimulate students’ intellectual curiosity, and students’prior knowledge.