The present study compared attitudes about the causes and optimal responses to mental illnesses of college students attending schools in Japan and in the United States. Independent sample t-tests were performed to assess differences between the national groups in their responses to 22 Likert-format items exploring different aspects of a biophysical versus a sociocultural conceptualization of the etiology of mental illnesses. Comparisons of the Japanese and American groups scores revealed differences on several of the dependent measures. The American students perceived there as being greater negative stigma associated with mental health problems than Japanese students. The U.S. students reported less willingness to seek treatment themselves or to recommend that a friend with a problem go to a mental health clinic for treatment. Significant differences in attitudes toward treatment were also found. U.S. participants endorsed the behavioral and humanistic etiological models more strongly than their Japanese counterparts, and were less supportive of the psychoanalytic perspective than Japanese students. The American students attributed treatment outcome more to patient than to therapist factors, saw patients as having greater control over their mental problems, and perceived thinking about ones problems as more valuable than the Japanese students. (Contains 12 references and 1 table.) (Author/GCP)