A number of attitudinal studies have examined support for the use of animals in research. However, on the whole they have come to rather different conclusions. In our reasearch, which is based on focus group discussions held in Denmark, we attempted to explain this variation by examining the way the relevant attitudes are formed. Although our participants had only limited knowledge of, and interest in, animal use in research, they were perfecly capable of developing reasoned attitudes to it by drawing on evaluative considerations concerning animal use in general. Furthermore, the evaluation of animal research involves a distinct experience of value conflict - between the possible human benefits, on the one hand, and a concern for costs to the animal, on the other. Different ways of dealing with this conflict gives rise ti different attitudinal stances on animal research: Disapprovers, Reserved, and Approvers. These stances, and their supporting lines of argument, are rather robust, as they are grounded in stable underlying values. However, at the same time they leave room for variable evaluations of different types of animal experiment. This facilitates shifts between approval and disapproval, especially for the Reserved who experience ambivalence. Future quantitative analyses should take into consideration that attitutes in the field of animal experimentation can be viewed (and measured) both at an underlying value-based level and at a context-specific level.