Code-switching is a common phenomenon that bilinguals engage in, including bilingual children. While many researchers have analyzed code-switching behaviors to better understand more about the language processes in bilingual children, few have examined how code-switching behavior affects a child's linguistic competence. This study thus sought to examine the relationship between code-switching and linguistic competency in bilingual children. Fifty-five English–Mandarin bilingual children aged 5 to 6 years were observed during classroom activities over five days (three hours each day). A number of different word roots and mean length of utterance for both languages, and a number of code-switched utterances for each child, were computed. English receptive vocabulary scores were also obtained. Additionally, teachers rated children's English and Mandarin language competencies approximately six months later. Correlational and hierarchical regression analyses support the argument that code-switching does not indicate linguistic incompetence. Instead, bilingual children's code-switching strongly suggests that it is a marker of linguistic competence.

Perhaps the most pervasive issue in the study of adult second language (L2) acquisition concerns the relative contribution of prior first language (L1) experience — the contrastive component — and universal grammatical principles — the constructive component — to this language learning process. Concern with this issue stems in part from basic linguistic and psychological questions about the nature of language learning in the adult and in part from the desire to integrate these two components within a framework that can provide for a unified theory of language learning in general. Current research within the field endeavors to isolate and quantify each of these two components in the adult L2 learning process.

Within this context, this paper reports results of an experimental study of the acquisition of anaphora in structures such as in (1) and (2).

• (1) Alice helped Mary when she walked through the garden.

• (2) Alice helped Mary when walking through the garden.

To what extent, if any, does Universal Grammar (UG) constrain second language (L2) acquisition? This is not only an empirical question, but one which is currently investigable. In this context, L2 acquisition is emerging as an important new domain of psycholinguistic research. Three logical possibilities have been articulated regarding the role of UG in L2 acquisition: The first is the “no access” hypothesis that claims that no aspect of UG is available to the L2 learner. The second is the “partial access” hypothesis that claims that only LI instantiated principles and LI instantiated parameter-values of UG are available to the learner. The third, called the “full access” hypothesis, asserts that UG in its entirety constrains L2 acquisition.

In this paper we argue that there is no compelling evidence to support either of the first two hypotheses. Moreover, we provide evidence concerning functional categories in L2 acquisition consistent with the claim that UG is fully available to the L2 learner (see also Flynn 1987; Li 1993; Martohardjono 1992; Schwartz & Sprouse 1991; Thomas 1991; White 1989). In addition, we will attempt to clarify some of currently unclear theoretical issues that arise with respect to positing UG as an explanatory theory of L2 acquisition. We will also investigate in some detail certain crucial methodological questions involved in experimentally testing the role of UG in L2 acquisition and finally, we will present a set of experimental results of our own supporting the “Full Access” hypothesis.

The target article advanced the null, unified and widely misinterpreted generative hypothesis regarding second language (L2) acquisition. Postulating that UG (Universal Grammar) constrains L2 knowledge growth does not entail identical developmental trajectories for L2 and first language (LI) acquisition; nor does it preclude a role for the L1. In embracing this hypothesis, we maintain a distinction between competence and performance. Those who conflate the two repeat fundamental and by no means unprecedented misconstruals of the generative enterprise, and more specifically, of the empirical content of the null hypothesis regarding L2 linguistic knowledge growth. We hope to have identified certain common goals, the adoption of which might constitute a firm foundation for continued productive interdisciplinary development of contemporary theoretical and experimental L2 acquisition research.

Universal Grammar (UG) can be interpreted as a constraint on the form of possible grammars (hypothesis space) or as a constraint on acquisition strategies (selection procedures). In this response to Herschensohn we reiterate the position outlined in Epstein et al. (1996a, r), that in the evaluation of L2 acquisition as a UG- constrained process the former (possible grammars/ knowledge states) is critical, not the latter. Selection procedures, on the other hand, are important in that they may have a bearing on development in language acquisition. We raise the possibility that differences in first and second language acquisition pertaining to both attainment of the end-state and course of development may derive from differences in selection procedures. We further suggest that for these reasons age effects in the attainment of nativelike proficiency must necessarily be separated from UG effects.

In this paper empirical data are presented that demonstrate significant differences in the manner in which two commonly used experimental tasks evaluate developing linguistic competence in adult second language (L2) learners. Results indicate that production tests principally evaluate a learner's developing structural competence in the L2. On the other hand, comprehension tests provide a less direct measure of structural competence and are significantly influenced by pragmatic context.

Fifty-one adult Spanish speakers at three levels of ESL ability were tested in both their elicited imitation (production) and act-out (comprehension) of complex sentences that were structurally identical. The stimuli varied in terms of the pre- and post-posing of a subordinate adverbial when clause and in terms of the direction of pronoun anaphora (forward and backward). Results from the production test indicate a significant effect of directionality, i.e., a preference for forward pronouns in post-posed clauses at the intermediate level. Results from the comprehension test did not show a significant directionality constraint at any level. They did, however, demonstrate a significant effect due to the use of a biasing pragmatic lead. Such findings are comparable to those found in early first language acquisition (Lust, Loveland, & Kornet, 1980). Implications of these findings for experimental methodology are discussed.