The differences in the academic achievements across semesters and areas of study of the children of new residents and residents studying in Taiwanese junior high schools have been ignored. The present study used the Keelung City Junior High School Students’ Learning Survey Database to explore the differences in the achievement in Chinese, English, mathematics, sociology, arts and literature, natural sciences, physical fitness, and comprehensive activities between the children of new residents and those of residents studying in junior high schools in different semesters. The data were analyzed at intervals of 1 year. 3 semesters of learning achievements of 1,586 students in 15 junior high schools were obtained from the database. Multivariate analysis of variance was used, and the following conclusions were drawn: The learning achievements of the children of new residents did not differ from those of residents in Chinese, English, mathematics, sociology, arts and literature, natural science, physical fitness, or comprehensive activities in the second semester of the first, second and third year. This contradicts the widely held belief that children of new residents have lower academic performance than children of residents. The findings of this study demonstrate that the learning achievements of the children of new residents and residents do not differ in the eight learning domains; schools, teachers, and students should disregard the aforementioned widely held belief. The study conclusions are discussed, and specific suggestions are provided.