This book is a pleasure for the second language (L2) researcher to read, and a challenge for the teacher of second language acquisition (L2A) theory to use. It offers an extremely clear and engaging introduction and overview of current L2A research from the generative 380 Reviews perspective. It successfully brings classical older findings to bear on the contemporary research issues. It highlights the most important issues in the field with admirable intellectual precision and honesty. At the same time, it is an introductory text that also has another agenda, namely, presenting and arguing for the author's own theory of second language development. Thus, it is not clear whether the text is intended exclusively as a teaching aid or as a research book. I am afraid the combination of the two is daunting for the unsuspecting reader.