Most comparative studies about China were challenged by many sinologists and educators for not grounding on representative samples. This research is mainly based on a Chinese data base collected from a random sample of more than 10,000 9th-grade students in the Second International Association for the Evaluation of Educational Achievement (IEA) Science Study (SISS) Extended Study (SES), a key project supported by the China State Commission of Education in the late 1980s. In contrast, the U.S. student data collected by the same IEA SISS instrument were appended to the SES data base. Analyses of the empirical data uncovered no significant difference in science achievement between the Chinese and American students. Given the fact that sizes of the representative samples in both countries were large and the difference of student achievement was still insignificant, this empirical result seemed to disconfirm the assertion of Chinese outperformance claimed by many scholars. Factors behind the disconfirmation are many, including significant regional differences in China, as well as different school investments in urban and rural communities. Contains 21 references. (Author/MKR)