The use of four-skills language exams to support the achievement of curriculum goals in Japan is an under-researched yet critical topic. This study focuses on washback from the Cambridge B1 Preliminary and B2 First exams, which were used as fixed-point tests at a senior high school. A mixed-methods approach was adopted, utilizing data from teachers and learners, and from tests, documents, surveys, interviews, and observations. Strong negative washback was observed from the Japanese university entrance exams, whereas no such effects were noted for the Cambridge exams, which were perceived as aligned with the curriculum and teaching objectives. The findings are discussed in relation to studies of washback in secondary school contexts worldwide.