Using a newly-developed group test of children's non-verbal reasoning ability (Naglieri's (1985) Matrix Analogies Test - Short Form [MAT-SF]), the study examined the performance of 451 Japanese Children, ages 6-12 years, and its relationship to school achievement. Test reliability was high. There were no significant gender differences. High achieving students scored significantly higher on this test in comparison with their average and low achieving peers. Across all age levels from 6 to 12, Japanese children consistently earned higher MAT-SF scores than North American samples (American and Canadian children). This result suggests that Japanese children may have an advantage in non-varbal or visuo-spatial reasoning in comparison with North American children. Whereas this study further supports the reliability and validity of the MAT-SF, it may be necessary to develop representative and relevant norms to aid test interpretation in non-North American countries and cultures.