The book How Languages are Learned (ISBN 978-0-19-454126-8) was written by Patsy M. Lightbown & Nina Spada, and first published in 1993. The fourth edition of this award-winning book was published in 2013, and it is extensively used by educators and linguists all around the world. Patsy M. Lightbown is a Distinguished Professor Emerita in Applied Linguistics at Concordia University, Montreal. She has been working on second language learning & teaching for more than forty years. She is an author, editor, consultant and an advisor. The co-author of this book, Nina Spada, is a Professor Emerita in the Second Language Education Program at University of Toronto. Her main research interest is form-focused instruction in classroom SLA. Furthermore, she was a Visiting Professor at Boğaziçi University, Turkey, in 2015. The book’s updated content provides educators some important information about recent research on second language learning. It also presents a number of useful activities and questions related to this field which will trigger critical thinking. The books itself is a good and reliable source that relates language acquisition theory and research to teaching and learning in the classroom.