There are few aspects of language which are more problematic than its discourse particles. The present study of discourse particles draws upon data from the London-Lund Corpus to show how the methods and tools of corpora can sharpen their description. The first part of the book provides a picture of the state of the art in discourse particle studies and introduces the theory and methodology for the analysis in the second part of the book. Discourse particles are analysed as elements which have been grammaticalised and as a result have certain properties and uses. The importance of linguistic and contextual cues such as text type, position in the discourse, prosody and collocation for analysing discourse particles is illustrated. The following chapters deal with specific discourse particles (now, oh, just, sort of, and that sort of thing, actually) on the basis of their empirical analysis in the London-Lund Corpus. Examples and extended extracts from many different text types are provided to illustrate what discourse particles are doing in discourse.