Millions of public-school students in the United States are identified as English language learners (ELLs), whose academic success is tied to their second language (L2) English education. Previous research in adult populations indicates that L2 proficiency is related to the contextual variable of the prevalence of one's first language (L1) among…

Millions engage in learning a Second Language (L2) using their mobile devices with a wide range of success. Concomitantly, there exists a growing interest in research on the effects of mobile-assisted language learning and predictors of learner outcomes (e.g., Loewen et al., 2020; Sudina & Plonsky, 2023). However, few of these apps and studies…

Conventional folk wisdom insists study abroad is an inherently valuable educational experience for young people. While traditional study abroad programs were typically a semester or a full year in duration, short-term study abroad programs of only a couple weeks are now the most common type of sojourn abroad. Problematically, evidence is mounting…

Second language (L2) writing has been determined to be influenced by what is read, with language learners tending to borrow words and short phrases from input texts while writing (e.g., Wang & Wang, 2015). This phenomenon is referred to as lexical alignment. Only one empirical study has investigated the influence that the linguistic complexity…

In the United States, the number of English Language Learners (ELLs) has steadily grown over the past decades. In the State of Delaware, the growth has been exponential. ELLs' academic underachievement in reading and math has remained a challenge for K-12 educational institutions. It has continued to be necessary to research the causes and…

Very high-level, functional ability in foreign languages is increasingly important in many walks of life. It is also very rare, and likely requires an early start and/or a special aptitude. This study investigated the extent to which aptitude for explicit learning, defined as "analytic ability" and aptitude for implicit learning, defined…

This inquiry analyzed the relationships between individual differences and gains made in oral proficiency of adult, second language learners of Spanish during one semester studying abroad. Oral proficiency was measured using a pre/post-SA Computerized Oral Proficiency Instrument (COPI, CAL, 2009). Gain scores were correlated with two cognitive…

Due to their unique profile as childhood bilinguals whose first language (L1) became weaker than their second language (L2), heritage speakers can shed light on three key issues in bilingualism--timing, input, and cross-linguistic interaction. The heritage speakers of focus in this dissertation are Korean second generation immigrants mainly…

This study examined the second language (L2) development of adult learners of Spanish at three levels of proficiency during and after a semester of instruction. A fundamental goal was to identify cognitive and psychosocial individual differences (IDs) that can explain between-learner variation over time in order to expand our understanding of the…

The primary aim of this dissertation was to investigate the relationship between speech perception and speech production difficulties among Japanese second language (L2) learners of English, in their learning complex syllable structures. Japanese L2 learners and American English controls were tested in a categorical ABX discrimination task of…

Bilingualism (Sanz, 2000), motivation (Pintrich, 1989), and language aptitude (Grigorenko, Sternberg, and Ehrman, 2000) are crucial individual differences that contribute to successful adult language learning. Since Gardner's (1985) seminal work on motivation, many studies have shown that motivation is dynamic and that it affects language…