This book is dedicated to the theory and practice of replication research in Second Language Acquisition and Applied Linguistics. A replication study repeats a previous study to discover if its findings are reliable and/or can be generalised to other circumstances. This edited volume brings together a number of experts who argue in favour of a more central role for replication research in Second Language Acquisition and Applied Linguistics. The book provides a theoretical argument to support this view, as well as practical examples and model replication studies. It includes advice on how best to set up and execute replication research, and how to write up the findings for presentation to a journal. A hardback version is available separately.