This volume offers a multidisciplinary view of cutting-edge research on bilingualism in Spanish and Portuguese-speaking regions, with the aim of building a bridge between sub-fields and approaches that often find themselves isolated from one another. The thirteen contributions in this volume offer a glimpse of the diversity of bilingualism present in the Hispanic and Lusophone world, shedding light on the sheer variety of speaker communities, language pairings (e.g., Spanish-English, Spanish-Basque, Spanish-Dutch, Portuguese-Spanish-English, Portuguese-English, Spanish-K'ichee Maya, and Spanish-Ixcatec) and speaker types (e.g., simultaneous bilinguals, and early and late sequential bilinguals). The diversity present in this collection of papers, both in empirical coverage and methodological and theoretical approaches, will be of interest to a wide range of students and researchers in bilingualism and Hispanic and Lusophone linguistics.