This book develops a new framework for describing the structure of multimodal documents: how language, image, layout and other modes of communication work together to convey meaning. Building on recent research in multimodal analysis, functional linguistics and information design, the book examines the textual, visual, and spatial aspects of page-based multimodal documents and employs an analytical model to describe and interpret their structure using the concepts of semiotic modes, medium and genre. To demonstrate and test this approach, the study performs a systematic, longitudinal analysis of a corpus of multimodal documents within a single genre: an extensively annotated corpus of tourist brochures produced between 1967-2008. The book provides multimodal discourse analysts with methodological tools to draw empirically-based conclusions about multimodal documents, and will be a valuable resource for researchers planning to develop and study multimodal corpora.