A study investigated how teaching students of English as a Second Language (ESL) about American culture would affect their attitudes toward both American and their native cultures. Subjects were 61 freshman and sophomore Thai students of English in a Thai university, divided into an experimental group (n=31), which attended a course on American culture, and a control group (n=30). On a questionnaire, the students ranked, in order of importance, 18 values important to Thais. They then rated Thais and Americans on five-point scales with respect to those values. In addition, students in the experimental group were interviewed after the semester. Results indicate that as predicted, attitudes toward the native culture did not change, but attitudes toward the American culture did not improve significantly either, contrary to expectation. It is concluded that while a course such as the one offered may not affect attitudes positively, it may be useful in a second language program if it helps meet students' language needs. Some statistical data are included. (MSE)