The present study explores the independent and interactive effects of task complexity and task modality on linguistic dimensions of second language (L2) performance and investigates how these effects are modulated by individual differences in working memory capacity. Thirty‐two intermediate learners of L2 Spanish completed less and more complex versions of the same type of argumentative task in the speaking and writing modalities. Perceived complexity questionnaires were administered as measures of cognitive load to both L2 learners and native speakers to independently validate task complexity manipulations. Task performance was analyzed in terms of general (complexity and accuracy) as well as task‐relevant (conjunctions) linguistic measures. Quantitative analyses revealed that task modality played a larger role than task complexity in inducing improved linguistic performance during task‐based work: Speaking tasks brought about more syntactically complex output while writing tasks favored more lexically complex and more accurate language. In addition, relationships of working memory capacity with various linguistic measures were attested, but only when the cognitive complexity of tasks was enhanced.

This study employed a multisite design to investigate the differential impact of deductive and guided inductive instruction for second language (L2) grammar development in ecologically valid classroom contexts. Students (n = 138) from eight intact third-year L2 Spanish classes in three public high schools in the United States received deductive instruction (n = 49), guided inductive instruction via PACE (n = 49), or no explicit instruction (n = 40) on the pronoun se in non-agentive constructions. Learning was measured with pre-, post-, and delayed posttests of auditory acceptability judgment and written production tasks. Multilevel models indicated that both instructional groups evidenced L2 development in producing se in non-agentive contexts, but only deductive groups were more accurate than controls for acceptability judgments. Findings also provided evidence of overgeneralization of se, especially for deductive groups. Intraclass correlation coefficients revealed variance related to the socio-local contexts of classrooms, teachers, and schools.

The first goal of this study was to examine how individual differences in initial L2 proficiency help explain L2 grammar development in oral production during short-term immersion abroad. The second goal of the study was methodological, and evaluated challenges that can result from operationalizing learners’ initial L2 proficiency as pretest performance on outcome measures (as opposed to independent proficiency measures) in analyses of L2 change. L2 Spanish learners participating in summer study abroad completed an elicited imitation task and two oral production tasks. Production data were analyzed for changes in relevant grammatical complexity and accuracy dimensions. Results indicate that learners with higher initial L2 proficiency experience greater L2 grammar advancement from short-term immersion, and that pretest performance can be an unreliable operational estimate of initial proficiency when analyzing L2 gains. We discuss findings following cognitive accounts of SLA, and highlight methodological implications for further research in immersion contexts and beyond.