Including contributions from a team of world-renowned international scholars, this volume is a state-of-the-art survey of second language speech research, showcasing new empirical studies alongside critical reviews of existing influential speech learning models. It presents a revised version of Flege's Speech Learning Model (SLM-r) for the first time, an update on a cornerstone of second language research. Chapters are grouped into five thematic areas: theoretical progress, segmental acquisition, acquiring suprasegmental features, accentedness and acoustic features, and cognitive and psychological variables. Every chapter provides new empirical evidence, offering new insights as well as challenges on aspects of the second language speech acquisition process. Comprehensive in its coverage, this book summarises the state of current research in second language phonology, and aims to shape and inspire future research in the field. It is an essential resource for academic researchers and students of second language acquisition, applied linguistics and phonetics and phonology.