Bilingualism Across the Lifespan explores the opportunities and challenges that are inherent in conducting cognitive research in an increasingly global and multilingual society. Divided into three sections, the book highlights the multifaceted and complex nature of bilingualism. The first section focuses on what every cognitive psychologist ought to know about bilingualism: the impact of bilingualism on cognition across the lifespan, the idea that bilinguals are not a special case, and the importance of bilingualism in cognitive research beyond language. The second section focuses on challenges inherent in bilingual research: diversity of bilingual experience, the assessment of proficiency, and finding matched comparison groups and materials. Finally, the book considers opportunities that are created when bilingualism is incorporated into the cognitive research enterprise. It illustrates how researchers of bilingualism leverage theory, methodology, and findings from single-language research, incorporate uniquely bilingual processes or representations, and target populations of bilinguals that help to establish universal properties. Bringing together leading international contributors, the book provides the reader with a better understanding of the nature of bilingualism and bilingual research as it relates to human cognition. It will be an essential read for all researchers and upper-level students of bilingualism and cognitive psychology more generally.