In several of the most widely read Spanish grammars an entire chapter is devoted to the two copular verbs in Spanish, ser “to be” and estar “to be”, and their many contexts of use (Bull, Reference Bull1965; Solé and Solé, Reference Solé and Solé1977; Whitley, Reference Whitley1986; Bosque and Demonte, Reference Bosque and Demonte1999; King and Suñer, Reference King and Suñer1999; Butt and Benjamin, Reference Butt and Benjamin2000). For some, the interest in this structure stems from the range of meanings that can be expressed with these two forms, whereas for others it is the variability in the use of these verbs with adjectives, existing between groups, individuals and particular social contexts, that generates inquiry. The combination of these two traits makes the contrast difficult to acquire and likely to be lost or weakened in contexts of language attrition or language contact (Silva-Corvalán, Reference Silva-Corvalán1986; Geeslin, Reference Geeslin2002) and this complexity makes the copula contrast in Spanish an excellent mechanism for exploring broader issues such as theories of acquisition and language change, which are of value to a readership well beyond those working directly on Spanish. After a brief description of the distribution of ser and estar, we provide an overview of the various theoretical descriptions of the copula contrast that exist and their implications for research on bilingualism. Next, we provide a description of the papers in this volume, and outline the areas of interest for readers whose research extends beyond Spanish grammar.

The Spanish copulas occur in several different syntactic frames, some of which allow only one of the two verbs and some of which permit either copula depending on the intended meaning. In general, ser occurs with noun phrases and adverbs of time, and with past participles to form the passive voice. When it does appear with adverbs of place, it does so in contexts that denote origin and occurrence. Estar also appears with adverbs of place and manner in contexts that express location and condition, as well as with the gerund to form the progressive tense. The full range of uses of ser and estar are examined in Silva-Corvalán and Montanari (this volume) and examples of each use are provided there. All other articles in this volume focus on a single context where ser and estar are both permissible under certain conditions. For example, ser appears with past participles to form the passive voice and estar occurs with past participles to show descriptions of states of being and with present participles to form progressive constructions. These uses are the focus of the study by Bruhn de Garavito and Valenzuela (this volume) and examples are provided in that article.

The syntactic frame that allows the greatest co-occurrence of ser and estar is the [copula + adjective] structure. By some accounts as much as 80 percent or more of the adjectives in Spanish allow this type of contrast (Vañó Cerdá, Reference Vañó Cerdá1982). Butt and Benjamin (Reference Butt and Benjamin2000) state that ser is used with adjectives to “refer to identity or nature, i.e., physical, moral and mental characteristics as opposed to conditions” (p. 399). King and Suñer (Reference King and Suñer1999) point out that ser “indicates the quality as a normal or expected characteristic” that “continues across time without suggesting the possibility of change or endpoint” (translation ours, p. 223). In contrast, estar is used with adjectives that indicate mood, physical condition, temporary physical appearance or other non-characteristic features in general (Butt and Benjamin, Reference Butt and Benjamin2000, p. 402) and can be used to “denote an impression, sensation or appearance” of the referent (Butt and Benjamin, Reference Butt and Benjamin2000, p. 405). King and Suñer (Reference King and Suñer1999) note that estar “makes the listener look for the contextual reason for which the speaker does not choose to classify the quality as an on-going characteristic” (translation ours, p. 223). This contrasting use is described in greater detail in the remaining three research papers included in this volume (Woolsey; Cheng, Lu and Giannakouros; and Geeslin and Guijarro-Fuentes).

Although the general concepts expressed in the aforementioned descriptions are accurate, the reality of language use is such that native speakers are able to express their own reading of a situation through copula choice and, thus, to-date there are no exceptionless rules. This is precisely why the phenomenon has stimulated such interest in the fields of first and second language acquisition and bilingual studies. Many volumes have focused exclusively on the Spanish copulas with adjectives (Falk, Reference Falk1979; Vaño-Cerdá, Reference Vañó Cerdá1982; Navas Ruíz, Reference Navas Ruiz1986; Porroche Ballesteros, Reference Porroche Ballesteros1990; Penadés Martínez, Reference Penadés Martínez1994; Geeslin, Reference Geeslin2005) and there are several theoretical approaches to explaining copula selection with adjectives including, but not limited to, Generative accounts, Functional accounts, and Variationist or Sociolinguistic accounts. Each of these accounts provides different mechanisms for explaining how copula selection works in the grammar while at the same time framing the question of how acquisition takes place, what needs to be acquired by learners and how language use is reflected in the grammar.

Within Generative theory, for example, the key distinction between the two copulas was formerly believed to be associated with perfectivity (Luján, Reference Luján1981), where estar was used in perfective contexts and ser was used in imperfective or ongoing contexts. That distinction has since been reformulated using Carlson's (Reference Carlson, Chierchia, Partee and Turner1989) predicate type distinction (Leonetti, Reference Leonetti1994; Fernández Leborans, Reference Fernández Leborans, Bosque and Demonte1999). What distinguishes the Generative accounts from all others is that the copula distinction is believed to be based on a single feature of the grammar, such that stage-level predicates are associated with estar and individual-level predicates are paired with ser. The key issue for first language acquirers is to learn that the predicate-type distinction (innate universal information) is relevant for the copula contrast in Spanish and the questions raised by researchers of second language acquisition have to do with the extent to which such innate information is available to L2 learners (see Bruhn de Garavito and Valenzuela, this volume, for a complete description of this approach and the relevant issues within Generative theory today).

In contrast with the Generative accounts that focus on a single unifying distinction, Functional accounts have focused on the relationship between pragmatic features such as frame of reference and characteristics of the adjective (e.g., directionality, or whether an adjective represents a quality that is bidirectional (such as happiness: one can become happier and sadder) or unidirectional (tall: one grows in a single direction)) and the referent (e.g., animacy) (Clements, Reference Clements1988, Reference Clements, Clements and Yoon2005; Delbecque, Reference Delbecque, Cerspoor, Dong and Sweetser1997). The key problem for L1 learners is to associate the various functions expressed by the copulas with the appropriate forms and, although learning may progress in a very different way, the issue is much the same for the second language learner. Functional accounts are based on actual language use data, but generally still seek to identify general tendencies that describe that use. Although no article in this volume takes a purely Functional approach, Cheng, Lu and Giannakouros; Geeslin and Guijarro-Fuentes; and Woolsey all employ variables gleaned from the insights of this theory.

In contrast with both Functional and Generative approaches, which seek to describe and predict copula selection, Variationist approaches hypothesize that many features, both linguistic and social, interact to determine the choices that speakers make. This means that while variables like predicate type (from Generative theory) or animacy of the referent (from Functionalist approaches) are viewed as potentially relevant players in this predictive model, no single variable is viewed as sufficient for explaining copula choice as a whole. Moreover, the form that the description of copula choice takes in these approaches is a statistical predictive model in which social and linguistic factors, including those beyond the level of the sentence, are taken into account (Cortés Torres, Reference Cortés Torres2004; Geeslin, Reference Geeslin2005; Salazar, Reference Salazar, Potowski and Cameron2007). While this approach is most frequently seen in studies of sociolinguistics, such as Geeslin and Guijarro-Fuentes (this volume), it is also the approach taken by Cheng, Lu and Giannakouros, and by Woolsey in their studies of second language learners (this volume). In the case of language learning under a Variationist approach, a learner must identify the relevant predictive factors and assign them the appropriate weight (i.e., importance) in order to reach native-like copula use (Preston, Reference Preston1993, Reference Preston, Bayley and Preston1996, Reference Preston, Swierzbin, Morris, Anderson, Klee and Tarone2000). One additional fact about the Variationist approach is that it does not rest on a theory of how acquisition takes place (first or second language) or what the mental structure of the grammar is. Instead, this theory is compatible with several models of learning, such as the Connectionist Model (see Mitchell and Myles, Reference Mitchell and Myles1998, p. 178 for discussion of the compatibility of the two) and, also with usage-based approaches such as the constructivist perspective described in detail in Silva-Corvalán and Montanari (this volume). This mutual compatibility across fields further opens the door for dialogue between researchers.

What becomes apparent as one reads the studies in the current volume is the tremendous benefit of reading across disciplines: from first and dual language acquisition to second language acquisition, from Generative accounts to Variationist ones, from one context of language contact to another, from usage-based accounts of acquisition to Generative accounts. The volume includes a study of the second language acquisition of the copula contrast by adult English-speaking learners in contexts of immediate reaction and comparison (Woolsey) which contrasts with a study of the second language acquisition of the passive by English-speaking adult learners conducted within a Generative framework (Bruhn de Garavito and Valenzuela) as well as a study of second language acquisition by Chinese-speaking adult learners in a free writing task (Cheng, Lu and Giannakouros). Silva-Corvalán and Montanari's work on child dual language acquisition provides insight into the role of input in language acquisition and the differences between first and second language acquisition. The effects of language contact on copula contrast are further explored in contexts of bilingualism in Spain, where there is contact with Basque, Catalan, Galician, and Valencian (Geeslin and Guijarro-Fuentes) and these findings are in turn, relevant for both first and second language contexts of bilingualism since both groups are included in that last study.

The value of the copula contrast in particular is that it opens the door to addressing several more general, long-standing questions that researchers on bilingualism regularly explore. For example, one notes that the treatment of the influence of one language on another varies dramatically across studies. While research on dual language acquisition credits the influence of English on Spanish with some of the patterns found as well as with the timing of copula acquisition, research on second language acquisition primarily shows influence on the duration of certain stages of acquisition rather than the forms produced by learners (see the commentary by Montrul (this volume) for an alternative view), and research on language contact among adult bilinguals shows varying degrees of influence of bilingualism in general on the grammars attested in the data. Additional issues that can be addressed through studies of the copula contrast are the role of input in language acquisition, the relationship of language acquisition (first and second) to language attrition or language change, and the role of social and contextual factors in language use by monolinguals and bilinguals. In the process of co-editing this volume, we have learned a tremendous amount about the research practices and theoretical foundations across disciplines and we hope to have provided a forum for continued interaction of this type. In this way, among others, the study of copula choice in Spanish is of interest to any scholar working on issues related to bilingualism, language acquisition and language use.