For nearly half a century, Professor M. A. K. Halliday has been enriching the discipline of linguistics with his keen insights into the social semiotic phenomenon we call language. This ten-volume series presents the seminal works of Professor Halliday. This first volume contains seventeen papers, including a new chapter entitled 'A Personal Perspective', in which Halliday offers his own current perspective on language and linguistic theory. The first part of the book presents early papers (1957-66) on basic concepts such as system, structure, class and rank. The second part highlights how, over the span of two decades (the 1960s to mid-1980s), Halliday developed systemic theory to account for linguistic phenomena extending upward through the ranks from word to clause to text. The last part, 'Construing and Abstracting', includes more recent work, in which Halliday discusses the issues confronting those who study linguistics, using Firth's description of linguistics - 'language turned back on itself'.