This mixed-methods study investigated the changes in Chinese students' motivation to learn English from elementary to high school and explored the reasons for these changes at different school levels. A motivational questionnaire was designed and administered to 3,777 elementary, junior high, and high school students, and follow-up interviews were then conducted with nine students in order to investigate their perceptions of their motivations. Seven subcomponents of motivation were identified. The statistical results revealed that junior high school students had the highest learning motivation, followed by those in elementary school and those in high school. The interview data indicated that parents' positive influence on students' English learning motivation was greater for junior high school students compared to elementary and high school students. Furthermore, the pressure of the college entrance examination had a negative influence on high school students' motivation to learn English. Based on the findings of this study, suggestions for further research are provided.