This book provides an overview of research on the cognition of bilingualism. In addition to identifying the most important characteristics of this research and offering a historical sketch in the first chapter, the bulk of the book deals with research on four bilingual processing topics. The first topic, lexico-semantic representation and organization in bilinguals, deals with how words and meanings are represented and connected in the bilingual mind. The second topic, cross-language priming, explores the bilingual lexicon by examining how exposure to words in one language may affect word recognition in another and leads to the discovery of an asymmetry in translation priming. The third topic, selective lexical access in bilinguals, examines whether bilinguals can selectively activate one language while suppressing the other. The research on the topic of code switching is intended to explore language control and language regulation mechanisms in bilinguals. The book ends in a chapter that reviews research on three topics beyond lexical processing: autobiographical memory in bilinguals, the representation and interaction of syntactic knowledge in bilinguals, and the consequences of bilingualism.