In this study, 185 British and 143 American undergraduates completed a battery of tests that measured attitudes toward animal testing and various individual difference variables. Attitudes toward animal testing factored into two interpretable factors: general attitudes toward animal testing, and animal welfare and conditions of testing. Overall, there was support for animal testing under the right conditions, although there was also concern for the welfare of animals and the conditions under which testing takes place. There were small but significant national difference on both factors (with Americans more positive about testing and less positive about animal welfare), and a significant sex difference on the first factor (women were more negative about testing). Correlation and regression analyses showed that there were few significant individual difference predictors of both factors. These results are discussed in relation to past and future work on attitudes toward animal testing.