This paper aims to examine the communicative value of discourse intonation by describing the four systems of discourse intonation (Brazil, 1985, 1997): prominence, tone, key and termination. The four systems of speaker intonational choices, each of which has a general meaning that takes on a local meaning within a particular context (Brazil, 1997: xi), are moment-by-moment judgments made by speakers on the basis of their assessment of the current state of understanding operating between the speakers. The paper begins with describing Brazil’s (1985, 1997) discourse intonation framework as purpose-driven, speaker controlled, interactive, co-operative, contextreferenced, and context-changing, followed by the description of each of the four systems illustrated with examples from naturally occurring speech. The data analysed in this paper come from the one-million-word Hong Kong Corpus of Spoken English (HKCSE) (prosodic) (Cheng et al., 2008) which is composed of the academic, business, conversation and public sub-corpora. The transcription notation used in the HKCSE (prosodic), as well as in this chapter, can be found in “Transcription conventions�? at the end of this chapter.