This article addresses methodological concerns in research on grammatical aspects of code-switching. Data from code-switching have the potential for a unique contribution to linguistics by giving us access to combinations of linguistic features that may be difficult (or impossible) to observe in monolingual data. Nonetheless, the use of code-switching data for linguistic inquiry is not without issues. In this paper, we focus on three methodological questions specific to code-switching research: (i) project design, (ii) experimental procedure and (iii) participant selection. Drawing on experimental data from both published works and in-progress projects, we highlight potential solutions to each methodological challenge, concluding that several solutions are often required to mitigate the impact of confounding variables. In line with previous work (e.g. Grosjean 1998, Gullberg, Indefrey & Muysken 2009), we suggest that researchers clearly report on their methodology. Our overall goal is to contribute to a dialogue on best practices in code-switching research.

The strategies used to signal information focus — the non-presupposed part of a sentence — in Spanish are under debate. The literature suggests that focus must appear rightmost; however, empirical evidence shows that speakers also realize focus in-situ. Moreover, there is limited research investigating the effects of language variety or knowledge of another language on focus marking. We address these questions via a paced elicited production task, testing speakers who learned Spanish naturalistically in infancy, including two groups of monolinguals and two groups of Spanish/English bilinguals: (a) Spanish natives who learned English after childhood, and (b) early bilinguals exposed to English in early childhood (heritage speakers). Confirming previous empirical studies, results show that all participant groups choose a similar range of focus-marking strategies, vastly preferring in-situ marking with rightmost marking used rarely. Results challenge both theoretical accounts of Spanish focus realization and expectations of special vulnerability at the syntax-discourse interface for bilinguals.

The grammars of bilinguals have been found to differ from those of monolinguals especially with regard to phenomena that involve the interface of syntax and discourse/pragmatics. This paper examines one syntax‒discourse interface phenomenon – presentational focus – in the grammars of heritage speakers of Spanish. The results of a contextualized acceptability judgment task indicate that lower proficiency heritage speakers show some variability in the structures they accept to realize focus, whereas higher proficiency heritage bilinguals pattern with monolinguals. These results suggest that some explanations of domain-specific vulnerability in bilingual grammars, including the Interface Hypothesis (Sorace, 2011), may need to be revised.

It is most often claimed that in Spanish constituents in narrow presentational or information focus appear rightmost, where they also receive main sentence stress, while shifting the stress to the focus in its canonical position is infelicitous. Some, however, claim that Spanish in fact has recourse to both strategies for making the focus prominent, and some recent quantitative work has shown support for this alternative view. The present paper contributes to this debate by experimentally testing the realization of presentational focus in Mexican Spanish using an acceptability judgment task. The results of the experiment reveal that, for these speakers, focused constituents need not be rightmost and can in fact be stressed in non-final position, contra the consensus view. These findings expand the database on focus in Spanish and indicate that theories of the prosody/syntax interface may need to be revised, especially those theories that motivate discourse-related syntactic movement based on the requirements of the prosody.