Much controversy has surrounded the use of animals in research. Empirically, much of the research has focused on how ethical individuals believe animal research to be, but it has not systematically examined the specific beliefs or reasons why individuals do or do not believe animal research to be ethical. Study 1 investigated the thematic foundations for the decision that animal research is or is not ethical by examining the content of essays written by participants explaining why they do or do (...) not support the use of animals in research. Results indicated that individuals who believed animal research was ethical most often referenced beliefs that animal research furthered human well-being, provided mechanisms to cure disease, and was well-regulated. Individuals who believed animal research was not ethical most often referenced beliefs that animal research was inhumane, unnecessary, and nonconsensual. Study 2 used the themes to create a scale to assess animal research attitudes. (shrink)