The use of the Internet is expected in foreign-language classrooms. The present study investigated and evaluated the effectiveness of a language course supplemented with online material for college-level Japanese learners. The study compared exam scores from students enrolled in traditional inclass instruction taught 5 consecutive days for 50 minutes "without online supplement" material with exam scores of students enrolled in traditional inclass instruction taught for 5 consecutive days for 50 minutes "with online supplement" material at home. The results suggest that language courses taught with online supplementary material make little difference in student test scores. This study suggests that students enrolled in the with-online course tend to stay in the course. Because 19% more students dropped out of the class in the comparison group by the end of the semester, compared to the experimental group, many of the high achievers could have raised the mean scores in the comparison group.