A study was made of cross-cultural patterns of achievement motivation in relationship to the mathematics achievement of Japanese and American boys and girls approximately 16 years of age. Sample sizes were 9,582 for the United States subjects (specifically, from Illinois) and 1,700 for the participants from Japan. Data came from performance on the High School Mathematics Test, which was administered during the spring term of the 1981-82 testing cycle. The test consisted of 60 items covering a range of mathematical topics, including algebra, geometry, modern math, data interpretation, and probability. A background questionnaire including two measures of achievement motivation (success/failure attributions and test anxiety) was completed by all students during the testing session. Results of correlational analyses revealed a number of associations between (1) gender, test comfort, and attribution variables; and (2) mathematics achievement performance in both within- and between-country comparisons. Specifically discussed are between- and within-country differences in the relationship between gender and mathematics performance, the relationship between test comfort and mathematics achievement performance, and between-country differences in relationships of attribution variables to mathematics achievement performance. It was concluded that current measures of achievement attribution are inadequate to assess motivational patterns in Japan, and that the much higher test scores of the Japanese students do not justify new policy recommendations, given the basic differences between the two countries.