This is corpus linguistics with a text linguistic focus. The volume concerns lexical inequality, the fact that some words and phrases share the quality of being key -- and thereby reflect or promote important themes -- in some textual contexts, while others do not. The patterning of words which differ in their centrality to text meaning is of increasing interest to corpus linguistics. At the same time software resources are yielding increasingly more detailed ways of identifying and studying the linkages between key words and phrases in text databases. This volume brings together work from some of the leading researchers in this field. It presents thirteen studies organized in three sections, the first containing a series of studies exploring the nature of keyness itself, then a set of five studies looking at keyness in specific discourse contexts, and then three studies with an educational focus.