This study examined why Chinese undergraduates performed better on an eight-item water-level task (WLT) than did American undergraduates. Based on cognitive developmental theory, it was hypothesized that ability to write Chinese characters may facilitate performance on the WLT. This hypothesis was tested along with an additional hypothesis that extensive training in mathematics, especially geometry, facilitates WLT performance. The participants were three groups of Chinese undergraduates: 295 native writers of Chinese from Beijing, China; 49 Chinese American writers of Chinese; and 129 Chinese Americans who could not write Chinese. Results suggest that the combined effect of writing Chinese and strong math training contribute significantly (p < .01) to skills necessary to master WLT. Among Chinese Americans, the effect of writing Chinese is significant for males (p < .05) but not for females. Scholastic Aptitude Test math score has a significant correlation (p < .001) with success on WLT.