The book begins with a comprehensive description of the major theoretical frameworks in discourse marker research. It provides a detailed analysis of prior second language research on discourse markers in several languages and the dominant avenues of inquiry. Additionally, this book engages in a discussion of methodology that can serve as a guide for future researchers on the topic. The data presented in this book provide a broad picture of both native speaker and learner production of discourse markers with implications for theoretical and formal understandings of pragmatic meaning. This book will be of particular interest to scholars in pragmatics for both second language acquisition and formal or theoretical perspectives.