We examined the relationship between personal moral philosophy, gender, and judgments of the effectiveness of materials designed by advocacy groups to sway public opinion about biomedical research using nonhuman animals. Twenty-six male and 74 female undergraduates evaluated 16 advertisements or brochures developed by groups which either supported or opposed animal research. The subjects also completed the Ethics Position Questionnaire (EPQ) and were offered the opportunity to sign postcards urging their congressperson to either support or eliminate federal funding of animal research. Females perceived the anti-animal research materials to be more effective than did the males, a difference that was not found in the case of the pro-animal research materials. The idealism dimension of the EPQ and gender accounted for a significant portion of the variation in judgments of the effectiveness of the anti-animal research materials but not the pro-animal research materials. The pattern of postcard signing was predicted by the subjects' evaluations of the stimulus materials but not gender or the EPQ variables.