Bilingualism is the cornerstone of linguistic proficiency and the ultimate objective of communication in our increasingly diverse and multilingual global context. François Grosjean, emeritus professor at the University of Neuchâtel, Switzerland, has synthesized his extensive contributions to the domain of bilingualism over more than four decades in a seminal work titled On Bilinguals and Bilingualism. This comprehensive volume meticulously documents his scholarly trajectory, delineating the evolution from his formative research initiatives to his current preeminence in the field. Specifically, the book provides a unique perspective on understanding bilingualism by combining personal stories of bilingual people with new research on bilingualism.The book contains 11 chapters on several subtopics in bilingualism, which can be categorized into three main parts. Part I (Chapter 1) introduces the author's personal experiences with bilingualism. Part II (Chapters 2–6) outlines the author's constructed concepts and theories related to bilingualism. Part III (Chapters 7–11) elaborates on the theoretical explanations of social phenomena related to bilingualism.In Part I, Chapter 1, the author introduces his personal journey as a bilingual person, transitioning from a monolingual background to becoming proficient in French, English, Italian, and American Sign Language. This narrative illustrates the significant influence of various language settings on one's linguistic skills and cultural identity. Grosjean also reflects on the evolution of bilingualism research, exploring the shifts in its definition, methods, and areas of focus through an analysis of his master's thesis, completed at Sorbonne University, and his subsequent work in the field. He notes that initial studies concentrated on linguistic knowledge and error analysis, with subsequent research shifting toward language use and cultural integration. Moreover, the author shares his insights from involvement in bilingual research initiatives, such as conducting English–French bilingual interviews with colleagues, which shed light on the real-world application and difficulties encountered by bilingual people in their language practices.Part II (Chapters 2–6) mainly covers the research experience of the author on the phenomenon of bilingualism, including the holistic view of bilingualism, the language modes, and the complementarity principle. These chapters collectively present the author's theoretical contributions to the study of bilingualism, offering a significant analytical framework for understanding the linguistic behavior and characteristics of bilingual speakers.In Chapter 2, the author critically examines the traditional monolingual perspective by analyzing two papers from 1985 and 1989. The author argues that bilingual people are not simply the combination of two monolingual speakers but rather possess a unique and specific linguistic configuration. Then, the author presents the holistic view of bilingualism, which refers to how bilinguals seamlessly integrate two languages into a unique linguistic system during their everyday communication. He introduces a definition of bilingualism as “the use of two or more languages (or dialogues) in everyday life,” a perspective that aligns closely with the views of many scholars, prioritizing language usage over linguistic proficiency (García & Li, 2014). This chapter also delves into the language skills, language acquisition processes, and the impact on language research of bilingual people, highlighting the importance of conducting independent and comprehensive research on bilinguals.Chapter 3 delves into the intricate language modes of bilingual people, exploring the shifts in their linguistic behavior when interacting with monolinguals and other bilinguals, as well as across various communication settings. This analysis encompasses the monolingual mode, the bilingual mode, and the transitional intermediate mode, as delineated by Grosjean. The chapter elucidates how bilinguals fine-tune their language activation and processing strategies in response to different linguistic contexts. Furthermore, it examines the consequences of these language modes on the production and perception of language.Chapter 4 introduces the complementarity principle, which describes how bilingual people typically acquire and use their languages for distinct objectives, across various domains of existence, and with different interlocutors. The proficiency levels in diverse linguistic competencies among bilinguals are subject to fluctuation, contingent on the specific language necessitated and the situational context in which it is applied. Moreover, Grosjean and his team have undertaken empirical investigations to quantify the linguistic practices of bilinguals through comprehensive questionnaire surveys and in-depth interviews. As a result of this research, they have crafted the Complementarity Index, a tool designed to measure the distribution of language usage and proficiency within particular domains.Chapter 5 delves into the mechanisms and strategies underlying the oral processing capabilities of bilingual people. Key phenomena such as the gender-marking effect, the base language influence, and the recognition of borrowed words are examined in depth. The chapter introduces the groundbreaking computational model of bilingual lexical access, called BIMOLA, which is grounded in the interactive activation framework. BIMOLA is designed to replicate the complex language network and cognitive processing strategies that bilinguals use during spoken word recognition, as proposed by Léwy and Grosjean (2008). This computational model provides a theoretical framework for understanding and interpreting the language processing abilities of bilinguals.Chapter 6 delves into the reciprocal interplay between languages, examining how one linguistic system affects the vocabulary, syntax, and other facets of another language in a predominantly monolingual context. It scrutinizes how these interlinguistic influences mirror the linguistic architecture and communicative patterns of bilingual people. Grosjean posits a distinction between static interference, dynamic interference, and the broader concepts of interference and transfer. Drawing on empirical evidence, the author elucidates the process of linguistic restructuring experienced by Spanish–French bilinguals in the French-speaking cantons of Switzerland. This research surfaces clear indications of the first language's enduring influence on the second language within an extended bilingual milieu. Furthermore, it validates the significance of this nuanced differentiation in comprehending and investigating the interplay between languages, as underscored by Grosjean and Py (1991).Part III (Chapters 7–11) predominantly extends the application of the bilingual theory established in Part II, providing a comprehensive analysis of various bilingual phenomena across social contexts, professional domains, and unique demographic groups. Collectively, these chapters delve into a richer understanding and a nuanced examination of bilingualism, spanning a wide array of dimensions—from individual particularities to societal collectives, from scholarly inquiry to practical application, and from linguistic competence to cultural identity.Chapter 7 delineates the nuanced distinction between bilingualism and biculturalism, clarifying that the ability to speak two languages does not inherently imply a dual cultural identity, and conversely, biculturalism is not solely the province of bilingual people. The author elucidates three defining attributes of biculturalism: active engagement in the lives of two or more cultural milieus, the capacity to adapt to disparate cultural norms and behaviors, and the synthesis of cultural attributes into a cohesive identity. Although these traits resonate with the definition of bicultural phenomena posited by Nguyen and Benet-Martinez (2007), the latter's conceptualization places a stronger emphasis on the integration of cultures. Subsequently, the author delves into the ways in which biculturals forge a unique sense of self and navigate the dual classifications imposed by disparate cultural communities. Additionally, the chapter challenges the prevalent notion that bilinguals undergo personality shifts with linguistic alternation, contending that changes in demeanor are more profoundly influenced by the social environment and contextual factors than by the language being spoken.Chapter 8 initially analyzes the similarities and differences in language use between deaf bilinguals and their hearing counterparts. It delves into the bilingual proficiency and bicultural experiences of deaf people, underscoring their distinctive and multifaceted status as a linguistic and cultural minority. Deaf people constitute a unique demographic, characterized by their bilingual and bicultural competencies (Ritzmann & Gore, 2019). The author advocates for attention to the bilingual education rights of deaf children, pointing out the importance of sign language and mainstream language (written or spoken) in their development. Concurrently, the chapter addresses the societal misconceptions surrounding deaf bilingualism and biculturalism, issuing a call for greater inclusivity and support. This advocacy is aimed at ensuring that deaf children have equitable access to and mastery of both languages, thereby enabling them to engage fully in both the deaf and hearing communities.Chapter 9 explores the complex statistical terrain of global bilingualism, shedding light on the nuanced differences and methodological challenges encountered when attempting to measure bilingual populations across different countries. By analyzing census data from the United States, Canada, Switzerland, and France, the chapter illuminates the extensive reach, intricate patterns, and shifting dynamics of bilingualism within these nations. Concurrently, it underscores the untapped potential and critical significance of bilingual statistics as a vital domain for scholarly inquiry, advocating for a more sophisticated approach to capturing the rich and varied aspects of bilingualism on a global scale.Chapter 10 focuses on the intriguing subset of people known as “special bilinguals,” a category that encompasses those whose professional roles or unique talents are inextricably linked to their bilingual proficiency. This group includes such diverse professions as bilingual authors, translators, and educators of second languages, as well as those whose work relies on the mastery of specific linguistic skills, such as pilots, air traffic controllers, and international journalists. Grosjean advocates for the establishment of a novel branch within bilingual research, dedicated to delving deeper into the contrasts and commonalities between special bilinguals and the broader population of ordinary bilinguals.In Chapter 11, Grosjean underscores the imperative of educating the public about bilingualism and biculturalism. He is convinced that the findings of bilingual research hold significant social implications, particularly in the realms of bilingual children's education and the linguistic rights of deaf children. Fellow scholars, such as Higgins and Lieberman (2016), concur with the necessity of guaranteeing language access for deaf children. Despite the fact that approximately half of the world's population is bilingual, research in this area remains scarce. Consequently, Grosjean is dedicated to the dissemination of bilingual insights to both the public and professional spheres. He accomplishes this mission through diverse platforms, including academic instruction, publications, blogging, and public lectures, thereby fostering a broader understanding and appreciation of bilingualism.Throughout these chapters, Grosjean showcases a profound and nuanced understanding of bilingualism, informed by his personal experiences and decades of scholarly inquiry. He delves into the linguistic intricacies of bilingualism and investigates its cultural and societal implications, providing robust theoretical foundations and empirical evidence to underpin the field of bilingual studies. His central thesis can be encapsulated thus: Bilingual people are not merely the sum of two monolingual parts but are distinct linguistic entities whose language abilities are influenced by a tapestry of social settings, communicative demands, and individual backgrounds. Grosjean underscores that bilingualism is a pervasive global occurrence, with bilinguals exhibiting a rich variety of language behaviors. Moreover, he challenges the notion that bilingualism is a linguistic anomaly, advocating instead for a perspective that recognizes it as an integral part of the human experience, deserving of equitable and unbiased consideration.In On Bilinguals and Bilingualism, the author offers readers a richly textured portrayal of the bilingual universe, drawn from more than four decades of immersion in bilingual research, as well as from personal experiences and insights. This work vividly illustrates the intricate and multifaceted nature of the bilingual experience. A standout attribute of the book is Grosjean's meticulous approach to simplifying complex concepts, breaking them down into coherent and accessible parts. Readers emerge with a deeper appreciation for the singular and nuanced aspects of bilingualism. Grosjean's talent for rendering complex ideas in straightforward language is truly remarkable, as is his ability to simultaneously provide subtle and nuanced explanations, which speaks to his profound expertise in the subject matter. Notably, Grosjean's contributions to the field extend beyond academic discourse. He is proactive in promoting the benefits of bilingual education to the wider public, to parents of bilingual children, and to educators, particularly in his advocacy for the bilingual educational rights of deaf children. This commitment highlights his role as a scholar with a strong sense of social responsibility.In many theoretical perspectives, Grosjean has maintained consistent perspectives with those previously held and has offered more comprehensive justifications. For the relationship between bilingualism and personality issues, Grosjean believes that it is the environment and the culture as a whole that cause the bilingual to change languages, along with attitudes, feelings, and behaviors. However, Grosjean has also revised certain viewpoints and introduced fresh perspectives, building on the foundation of the original argument. In two articles published in 1985 and 1989, he emphasized significant distinctions between bilinguals and monolinguals. Grosjean highlights in the book that such distinctions should not be interpreted as monolinguals being linguistically disadvantaged. He asserts that both monolinguals and bilinguals have the potential to become highly skilled communicators.In general, this book offers a thorough and panoramic survey of the historical development and contemporary landscape of bilingualism research. The book delves into the multifaceted aspects of bilingual phenomena, examining language modes, the complementarity principle, cross-linguistic influences, and the formation of a bicultural identity. The author skillfully weaves personal bilingual insights with a wealth of research illustrations, leading to an engaging and methodical scholarly discourse within the realm of bilingual studies. This integrative method brings theoretical explanations to life, rendering them concrete, precise, and accessible to a broad audience.A further commendable feature of the book is Grosjean's dedication to updating the reader on the shifting focal points and advancements within the field. Across its pages, he engagingly discusses the reactions to, replications of, and extensions of his work, showcasing the development and refinement of his theories over the years. This approach not only heightens the book's scholarly significance but also fosters a spirit of critical thinking among readers. Thus, this volume is an invaluable resource for courses in psycholinguistics, linguistics, cognitive sciences, speech and language pathology, and the study of bilingualism, as well as first and second language acquisition. It is an apt text for academics and students in the disciplines of linguistics, psychology, education, and cross-cultural communication, and it holds broad appeal for any reader with a keen interest in bilingual phenomena, particularly for those seeking to delve deeper into the lived experiences of bilingual people, the strategies of bilingual education, and the social dynamics of bilingual communities.Although On Bilinguals and Bilingualism offers significant insights, it is important to acknowledge certain limitations of the book. First, the temporal scope of the book is broad, encompassing a wide range of studies and examples. This extensive coverage means that some of the discussions are grounded in earlier theories and research outcomes, which may diminish in relevance over time. Second, there is a lack of integration between theory and practice. Although the book covers many theoretical viewpoints and academic research, the actual cases of bilinguals included are limited in scope and quantity, and there is little practical application, especially in terms of specific guidance on how to cultivate bilingual children in the education field and family environment. Last, although the book emphasizes the positive impacts of bilingual abilities, it falls short in discussing the negative social biases and pressures that bilingual people may encounter in certain environments.In conclusion, On Bilinguals and Bilingualism by François Grosjean is a must-read for anyone intrigued by the complexities of bilingualism and its associated disciplines. Grosjean's opus marks a substantial advancement in the domain of bilingual research and offers an invaluable trove of knowledge for language learners and enthusiasts.