This study explored the extent of measurable differences in performance on Piagetian tasks among six year olds who are exposed to one or two languages. Subjects (N=120) were divided into four groups: (1) native English-speaking Anglo-Americans who live in the United States; (2) native Japanese-speaking Japanese who live in Japan; (3) native English-speaking Anglo-Americans who are exposed to Japanese and live in Japan; and (4) native Japanese speaking Japanese who are exposed to English and live in the United States. Nine null hypotheses were formulated to test for significant differences among the groups on the performance of three different Piagetian tasks which were individually administered. The F-test (p<.01), Q-test (p<.05), and t-test (p<.01) were used for underlying distribution of the test statistics. All subjects (Japanese and American) exposed to two languages performed significantly better on the three Piagetian tasks as compared to subjects exposed to one language. There were no significant differences in performance on the three Piagetian tasks between: (1) Japanese with one language/one culture and Anglo-Americans with one language; and (2) Japanese with two languages/two cultures and Anglo-Americans with two languages. Two tables are included. (Contains 68 references.) (Author)