Countering traditional monolingual ideologies that associate multilingual development with various deficiencies, more recent research probes into potential advantages of this developmental experience. The discussion about putative multilingual advantages remains highly controversial and also emotional, as it affects far-reaching policy decisions. The chapter attempts to provide an objective state-of-the-art report, discussing research findings on executive function (control), cognitive reserve, cognitive development, educational attainment, and metalinguistic awareness. It furthermore tries to identify the boundary conditions that help to explain why some studies report positive results while others do not. Current research suggests that the characteristics of the speaker groups sampled, especially in terms of their type of bilingualism and multilingualism (balanced, unbalanced, heritage speakers, etc.), offer important clues for a better understanding of this domain. Moreover, the social prestige associated with the languages studied appears to influence the results considerably. Language users are not deterministic machines, but react to social pressure in intelligent ways.

Chapter 3 explores cross-linguistic influence and various theories thereof in multilingual settings in which more than two languages interact with one another. It is specifically interested in the direction and strength of such influence, contingent on parameters like age of onset, proficiency, L1 and L2 status, linguistic and typological proximity, recency of use, language dominance, as well as various others. It identifies cross-linguistic influence as the more encompassing concept in comparison to the traditional notion of transfer widely used in second language acquisition studies. It also discusses the relationship between cross-linguistic influence and language interdependence, as proposed in education studies. While language interdependence builds on the proficiency-enhancing qualities of multilingualism (qua metalinguistic awareness), cross-linguistic influence can be both facilitative and inhibitory, the latter manifesting itself as interference. Crucially, non-facilitative transfer only arises within a normative system. Moreover, the mechanisms underlying cross-linguistic influence show important parallels to those identified in language contact studies with its focus on contact-induced language change.

Chapter 5 is based on the conviction that the problems dealt with in the preceding chapters need to be embedded into the larger multilingual ecologies in which they occur. Since language dominance has proven an important predictor of cross-linguistic influence, which, in turn, determines the acquisition of additional languages, including expectable benefits of previous multilingual experience, one needs to follow up on the factors that are responsible for language dominance. Evidently, these factors are related to or the result of various issues of language policy and planning – both explicit and implicit – that shape the language ecology encountered in a particular region, even down to the nuclear family. It makes a difference whether one studies these issues in traditional European monolingual ecologies where other languages are learnt as classic second or foreign languages, in de jure monolingual ecologies with high numbers of immigrant speakers of other languages, in bilingual territories where the two languages enjoy the same status, coexist peacefully, and where the number of balanced bilinguals is high, in bilingual or multilingual areas with minority languages or stigmatized languages, or in highly multilingual ecologies with a common lingua franca.

Chapter 4 explores potential advantages of multilingual upbringing in relation to further language development. It argues that any such advantages play out more forcefully and are easier to identify in regard to general proficiencies rather than specific grammatical phenomena. Chapter 4 further argues that type of bilingualism, as operationalized in terms of language dominance, and the type of language knowledge investigated play a pivotal role for understanding language learning processes against a multilingual substrate. Cross-linguistic influence, as observable in different grammatical domains and the lexicon, can aid additional language acquisition by means of cumulative enhancement, but certain constellations also produce inhibitory effects. The assumption of universally facilitating effects has turned out to be overly optimistic and needs to be tempered. Much of the discussion in Chapter 4 is based on the acquisition of English as an additional language in bilingual heritage contexts (third language acquisition). Besides general CEFR-proficiencies, the case studies concern determiners, subject–verb agreement, tense and aspect, word order, and lexical cross-linguistic influence.

Monolingualism, bilingualism, and multilingualism represent concepts of individual upbringing and social organization of extreme impact and scope. All in all, the book attempted to guide the reader from a multilingualism-as-problem to a multilingualism-as-resource perspective. However, it also argued that multilingualism cannot work wonders and should not be considered a goal in itself. Running a multilingual society can produce many beneficial effects, but maintaining several languages at the same time also incurs costs that a society must be prepared to burden and share. It is crucial to know which boundary conditions tip the balance from burden to benefit, or vice versa. The book further argues for a continuum from monolingualism to multilingualism based on the dimensions of homogeneity and heterogeneity. It further introduces a novel typology of English in multilingual contexts, distinguishing between English in heritage contexts, English in bilingual heritage contexts, English in contexts of balanced bilingualism, English in indigenous multilingual contexts, English in postcolonial multilingual contexts, and English as a lingua franca in modern multilingual immigrant contexts.

So far, in these lectures, we have seen how an unfolding denotational text-in-context figurates the identities and interactional textual projects of particular participants, furthering their apparent goals in the interaction. Our analysis of the transcript of Mr. A and Ms. C as well as that of Mr. Black and Ms. Mercer in Lecture 3 demonstrated how deictics (indexical referentials) and social indexicals – as elements of pragmatic paradigms – are centrally involved as they are metricalized into segmentations of phases in discursive space-time. We also saw that these unique communicative events, like all events, are interdiscursively connected in fields of interactions.

In the last lecture, we set the background for being able to talk at all about “linguistic relativity” by reviewing the post-Enlightenment concern with language as the instrument of rationality – grammar and logic in the medieval trivium – as well as by introducing the problem that linguistic diversity poses for it, let alone the diversity of the cast-off third member of the trivium, rhetoric, that is, the socioculturally effective use of language in events of communication. We then developed the necessary strategy of structural or formal linguistics if it is to be an empirical science of language by first considering the phonologico-phonetic categoriality of language. We then expanded this analysis by considering other planes of language, an approach we develop here. Our analysis suggested that “meanings” or “concepts” as projected from formal distributional categorizations.

Differential Object Marking (DOM) is vulnerable to change in heritage speakers of Spanish and heritage speakers of Hindi. DOM is also vulnerable to L1 attrition in Spanish-speaking first-generation immigrants but not in Hindi immigrants. This chapter examines DOM vulnerability in Romanian. The chapter describes the sociolinguistic characteristics of the Romanian-speaking population in the United, followed by a summary of the overall results of the linguistic background questionnaire and the linguistic tasks. The overall results show that, compared to the Spanish and Hindi-speaking populations, the Romanian-speaking population in the United States is far less numerous, yet their Romanian language skills remain relatively strong compared to the other two groups. The accuracy with DOM of the first-generation Romanian immigrants on all linguistic measures did not differ from those of the Romanian speakers in Romania. Just like in the Hindi study, there appears to be no evidence of language change in the homeland nor signs of attrition of this phenomenon in the first-generation adult immigrants sampled in this study. Yet, DOM and accusative clitic doubling (CD) were found to be somewhat vulnerable to omission in heritage speakers, especially in those exposed to English since birth or very early in life (the simultaneous bilinguals).