According to the mental model theory, reasoners build an initial model representing the information given in the premises. In the context of relational reasoning, the question arises as to which kind of representation is used to cope with indeterminate or multimodel problems. The present article presents an array of possible answers arising from the initial construction of complete explicit models, partial explicit models, partial implicit models, a single "isomeric" model, or a single annotated model. Predictions generated from these views are tested in two experiments that vary the problem structure and the number of models consistent with the premises. Analyses of the premise processing times, answering times and accuracy show that the annotated model yields the best fit of the data. Implications of these findings for the mental model theory as developed for relational reasoning are discussed.In linear syllogisms such as George is heavier than Tony and Tony is heavier than Jacques, people easily infer that George is heavier than Jacques. The findings collected in numerous studies substantiate the hypothesis that people solve such problems by constructing a linear array with the largest values at the top and the smallest ones at the bottom or alternatively by constructing a left-to-right array (see, e.g., De Soto, London, & Handel, 1965;Huttenlocher, 1968;Potts, 1974). The review by Evans, Newstead, and Byrne (1993, chap. 6) shows that this view yields the best summary of the findings reported in the literature. The usage of such an integrated spatial representation seems to be independent of the relational content and works both for determinate problems (as in the example above) and for indeterminate problems as, for example, in George is heavier than Jacques and George is heavier than Tony, where the relation between Jacques and Tony remains unresolved. Support for all this has been accumulated in