This book is the first to combine interests in two currently popular approaches to language description, both of which are based on the observation of naturally-occurring, as opposed to invented, language. Systemic Functional Linguistics is a theory that focuses on meaning, choice and probability in language and on language as a social phenomenon. Corpus Linguistics is a practice, rather than a theory: a corpus is a large collection of texts that are used as the basis for language description. It is natural that SFL should turn to corpora as a source of information about grammatical preference, probability and variety, and some of the papers in this collection explore this dimension of the interaction between system and corpus. Conversely, corpus linguists have made generalisations about language that contextualize but also challenge the theories of SFL. Some of the papers in the collection expand on this theme. A concluding paper by M.A.K. Halliday responds to the issues raised. The book will therefore be of interest to students and researchers involved in either of these two influential topics in linguistics.