Discourse topics are a frequently mentioned but rarely operationalised concept in linguistics. Taking a text linguistic approach and defining discourse topics as clusterings of concepts, this book examines and compares methods for investigating topic boundaries, topic identification and topic development. The first book to be devoted to topics in extended discourse, Discourse Topics examines topics in several genres and generates new insights into the nature of discourse topics that challenge the status quo. It is essential reading for researchers in linguistics, discourse analysis, natural language processing and psychology whose work concerns topics.