As is explicitly claimed in the introduction by the editors, “this book is manifestly about multilingualism rather than bilingualism…” (p. 1). This slim volume presents an attempt to provide a framework for studying multilingualism as a field of inquiry separate from bilingualism. It is largely a psycholinguistic effort to explore multilingualism, and much of its discussion is situated in the European context. In particular, following the introduction, seven clearly organized chapters are devoted to terminologies and methodologies of multilingualism as well as its main research areas and future directions. In chapter 2, Kemp provides an in-depth analysis of defining multilingualism and related terms. Franceschini, in chapter 3, offers broad prospects for future research in multilingualism. Chapter 4 by De Angelis and Dewaele and chapter 5 by Ó Laoire and Singleton both deal with crosslinguistic influence (CLI). Chapter 4 offers a historical overview of the development of CLI research, and chapter 5 reports on two empirical studies examining psychotypological factor in third-language acquisition (TLA). Aronin and Hufeisen’s chapter 6 outlines an extensive array of research methods and approaches, and it identifies contemporary multilingualism as characterized by complexity, liminality, and suffusiveness. It is especially noteworthy that in this chapter, Aronin and Hufeisen propose the term multilingualism studies as a label for the field. Chapter 7 by Cenoz and Jessner explores multilingual education through the lens of TLA, with a special focus on age effects. Ecke, in chapter 8, sets up a comprehensive database of multilingualism resources, such as associations, journals, and conferences. In a brief conclusion, remarking on the first threshold where research in bilingualism and SLA turned away from monolingual perspective, the editors highlight the central thesis of this volume: Given its complexity and distinction from bilingualism, multilingualism deserves inquiry in its own right. The editors suggest that doing so will be crossing the second threshold. Overall this volume is an important contribution to establishing multilingualism studies as a separate discipline, and it offers an exciting prospect for further exploration.