This third volume in the Collected Works of M.A.K.Halliday series includes papers that explore different aspects of language from a systemic functional perspective.The papers are organized into three sections:the place of linguistics as a discipline;linguistics and language; and language as social semiotic.In addition,there is a new work from Professor Halliday,entitled'On the"architecture"of human language,'in which he focuses on the assumptions or working hypotheses that enabled him to explore important questions about this massive semiotic power called'language'.