This study longitudinally examined the effects of cognitive and sociopsychological individual differences (aptitude, motivation, personality) and the quantity and quality of second language (L2) experience on L2 speech gains in naturalistic settings. We elicited L2 spontaneous speech from 50 Chinese learners of English at the beginning and the end…

Some second language (L2) acquisition researchers have suggested that learners should be made aware of cross-linguistic similarity for them to benefit from cognateness. To test this assumption, we ran two longitudinal classroom quasi-experiments with Polish learners of English. We chose 30 Polish-English cognates, 30 false cognates, and 30…

This study investigated the influence of cognitive ability on bilingual children's vocabulary development in both their languages. Sixty-nine bilingual immigrant children participated, with data collected at three annual intervals. At Time 1, the participants were 5 or 6 years old. Receptive vocabulary was tested in the minority (Turkish, Tarifit)…

In bilinguals and second language learners, the native (L1) and nonnative (L2) languages coexist and interact. The L1 influences L2 production via forward transfer, as is seen with foreign accents. However, language transfer is bidirectional: even brief experience with an L2 can affect L1 production, via backward transfer. Here, we review the…

The Foreign Language Classroom Anxiety Scale (FLCAS) has been challenged on the grounds that it may also assess language learning skills. In this study, 128 students who had been administered measures of first language (L1) skills in elementary school were followed from 1st to 10th grade. Fifty-three students had completed second language (L2)…

Researching the longitudinal development of second language (L2) learners is essential to understanding influences on their success. This 7-year study of oral skills in adult immigrant learners of English as a second language evaluated comprehensibility, fluency, and accentedness in first-language (L1) Mandarin and Slavic language speakers. The…

The study examined differences in reading achievement and mastery skill development among Grade-6 students with different language background profiles, using cognitive diagnosis modeling applied to large-scale provincial reading test performance data. Our analyses revealed that students residing in various home language environments show different…

Variability in achievement across learners is a hallmark of second language (L2) learning, especially in academic-based learning. The Twins Early Development Study (TEDS), based on a large, population-representative sample in the United Kingdom, provides the first opportunity to examine individual differences in second language achievement in a…

In this article, I describe studies conducted over 25 years with secondary and post-secondary L2 learners in the United States. The evidence from these studies shows that there are important connections between students' early L1 skills and their L2 aptitude and L2 proficiency and that individual differences in students' L1 skills in elementary…

This longitudinal study investigates the development of writing proficiency in English as a foreign language (EFL), in contrast to the development of first language (L1) writing proficiency in Dutch L1, in a sample of almost 400 secondary school students in the Netherlands. Students performed several writing tasks in both languages in three…

This quasi-experimental study reports on a 10-month classroom-based longitudinal investigation, exploring the potential of authentic materials to develop Japanese learners' communicative competence in English. Sixty-two second-year university students were assigned to either a control group receiving textbook input or an experimental group…