This text is the first holistic research overview and practical methodological guide for social network analysis in second language acquisition, examining how to study learner social networks and how to use network data to predict language learner behavior and identity. Authors Kristen Kennedy Terry and Robert Bayley lay out the history of social network analysis in sociolinguistics, discuss the state of the art in empirical findings in applications to language acquisition, offer how-to guidance and best practices for planning, conducting, and understanding this research, and authoritatively set the agenda for future work. With a variety of helpful features like case studies, suggested research projects, discussion questions, and recommended further reading, this book will be an invaluable resource to students and researchers of second language acquisition, sociolinguistics, education, and beyond.