Traditionally, metaphor has been seen as a threat to the scientific maxims of accuracy, truth, and explicitness. This view is still reflected in academic writing conventions, but has been opposed by research suggesting that metaphor is an indispensable part of natural language. So far, most studies on metaphor in academic prose have been conducted on a small scale or restricted in their focus, investigating only small sets of metaphors, or have lacked a transparent method of metaphor identification. This book presents a new type of metaphor research into written academic discourse. On the basis of a systematic and consistent method which identified metaphorical language on a word-by-word basis, it constructs the first register profile of academic prose that takes into account metaphor. Patterns of metaphorical language use in academic prose are described in terms of lexico-grammatical forms, communicative functions, and underlying conceptual structures. A hand-annotated corpus of 190,000 words of natural language, allowed for consistent cross-register comparison with news, fiction, and conversation. The work not only approaches metaphor from a cognitive-linguistic, sociolinguistic, and discourse-analytical angle, but also from a psycholinguistic one, investigating the processing of metaphorical language in academic discourse as influenced by academic expertise and metaphor conventionality. This research is useful for anyone interested in the study of academic discourse, metaphor in specialized discourse, and register variation in general. In addition to furthering our knowledge of the characteristics of academic discourse, its focus on methodology will be helpful to those concerned with the methodological aspects of metaphor analysis.