This book is a reference that provides an overview of the major work done in Spanish second language acquisition. It contains a section on the major theoretical approaches (generative, cognitive, and sociocultural), a section on the major elements of language (phonemes, morphemes, tense, syntax, discourse, pragmatics), and a concluding chapter on the effects of different instructional approaches. We are publishing it primarily for its potential course use, but the quality of the contributors will also attract attention from scholars.