The present study investigated whether psychological inflexibility is related to disordered eating in Japanese undergraduate students and compared the strength and pattern of the associations with effects in a sample of undergraduate students from the United States. Data from 200 Japanese (n _female = 100) and 481 U.S. (n _female = 380) college students were used. Contrary to prediction, female gender and higher body mass index (BMI), but not psychological inflexibility, were uniquely related to higher levels of disordered eating while controlling for age and psychological distress in the Japanese group. In the U.S. group, greater psychological inflexibility was the only variable that was uniquely related to higher levels of disordered eating after controlling for other study variables. Our findings suggest that psychological inflexibility may not be a useful concept for understanding disordered eating within Japanese college students.