"This volume is a rich resource for anyone who wishes to find out how Systemic Functional Linguistics approaches the task of describing language, or to deepen their understanding of key concepts in SFL and the relationships between them. The book is no mere dictionary-type list of entries: there is a consistent and fully-justified emphasis on the central importance of understanding the place of each item in the overall architecture of the theory. This is highlighted not only through a network of cross-references to other entries but through a range of ingenious and effective visual representations of broader areas of the model. The stress on locating concepts in their wider context reflects the fundamentally systemic nature of the enterprise: grammatics (the theory of grammar) is treated in the same way as the grammar (the description of language or languages), as systems of interlocking choices. The book does not attempt to minimise the inherent complexity and extravagance of language, or the corresponding complexity and extravagance required in any adequate descriptive or theoretical account of langua≥ but it establishes clear pathways through the complexity by shunting in an illuminating way between concise, lucid explanations of individual terms and impressively panoramic overviews of the systems in which these terms play a part. The picture that emerges from viewing SFL through the window of technical terms "those meanings of the theory that have been lexicalised within the register or registers of that theory", as the Introduction puts it is unexpectedly comprehensive and rewarding. This is a book that sets new standards of coverage, depth and coherence for glossaries of technical terms in any field." - Geoff Thompson is Senior Lecturer and Director of the MA TESOL at the School of English, University of Liverpool, UK.