Defining metaphor as "seeing a concept from one class in terms of a concept from another class," a study was devised that analyzed the degree to which two concepts occupy dissimilar positions with respect to their category or domain (within-domain distance), and the degree to which categories themselves are dissimilar (between-domain distance). Preliminary to the study, nine groups of subjects rated the distances among stimuli from eight domains as a basis for two experiments. In the first experiment, one group of subjects rated the aptness of 64 metaphors while another group rated the comprehensibility of the same metaphors. Aptness related positively to between-domain distance and negatively to within-domain distance, but showed no relationship to overall distance. Comprehensibility related strongly to aptness. In the second experiment, subjects ranked a set of alternatives as possible completions of metaphors. In one group, all of the possible completions were from a single domain; in the other group, all were from different domains. In both groups the rank order of the within-domain distances of a set of alternatives correlated with the relative popularity of the alternatives. The overall results of the study consistently supported a domains-interaction view of metaphor. (Tables are appended.) (Author/MAI)