Identifying metaphorically used words in the way we have proposed in the other articles in this special issue inevitably leads to the detection of recurring structural patterns of metaphor usage. It is the aim of the present article to explore these patterns in a systematic fashion and develop a taxonomy of the propositional structure of metaphors. As a preliminary step, a decision has to be made about the units of discourse within which one may examine patterns of the propositional structure of metaphorical language. This article has adopted the position that all non-downgraded clauses, in the manner of Mann and Thompson's Rhetorical Structure Theory (1988), would be the most eligible candidate. Inside the boundaries of these text units, we have found single as opposed to multiple metaphor, simple as opposed to complex metaphor, pure as opposed to mixed metaphor, and restricted as opposed to extended metaphor. Moreover, these four oppositions may also be combined with each other. Of the 16 logically possible combinations, 2 are ruled out, but the other 14 combinations present just as many structural types of metaphor. We then move on to discuss how such a taxonomy may be used in the quantitative characterization of the metaphorical style of an author. We show how the taxonomy may be applied at various levels of measurement, ranging from the word through the proposition to the text unit itself. Another possibility is to perform these measurements at the level of metaphorical mappings, which is the option we have chosen to apply to two stretches of fiction, by Sara Maitland and Salman Rushdie. The provisional results of this analysis are then finally presented and discussed. [Copyright 2002 Sage Publications Ltd.] (LLBA 2002, vol. 36, n. 3)