The fastest-growing sector of the American school population is the limited English proficient (LEP) students, those students whose native language is not English. When mainstreamed they are usually enrolled in physical education, art, and music classes first. The students then enter mathematics classes under the assumption that mathematics is computation-bound and easier to manage. These students are a new challenge to mathematics teachers who are incorporating new ideas of teaching and learning presented in the reformed state mathematics curricula. This is a case study of an eighth-grade LEP student from Japan. The purpose of the study was to examine the effects that culture and language have in the mathematics classroom: What factors influence the adjustment and experience of the student in the new school setting and enhance his or her achievement in mathematics? Data were collected over five weeks in the form of field notes of observation and interview and also various mathematics-related artifacts. Findings indicate that factors such as teaching differences between cultures, communication, and method of assessment and evaluation greatly influence the adjustment and experience of the LEP student in American classrooms and achievement in mathematics. Contains 31 references. (PVD)