This paper examines evidence for relationships among individual differences (IDs) in L1 achievement, L2 aptitude, and L2 achievement. It begins by providing an overview of my academic journey from L1 educator to L2 researcher and explains the development of the Linguistic Coding Differences Hypothesis (LCDH). Next, I review Peter Skehan's…

Studies with U.S. secondary second language (L2) learners have revealed individual differences (IDs) in first language (L1) skills and L2 aptitude and shown that these IDs are related to L2 achievement and proficiency. In this study, U.S. students were administered measures of L1 achievement, L1 cognitive processing, and L2 aptitude; followed…

Second language (L2) educators have proposed a unique anxiety for general L2 learning and an anxiety specific to L2 reading. Since the early 1990s, the L2 anxiety concept has been challenged on theoretical and empirical grounds. In this investigation, U.S. high school L2 learners were administered the Foreign Language Reading Anxiety Scale (FLRAS)…

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)…

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…

The study examined whether individual differences in high school first language (L1) reading achievement and print exposure would account for unique variance in second language (L2) written (word decoding, spelling, writing, reading comprehension) and oral (listening/speaking) proficiency after adjusting for the effects of early L1 literacy and…

A factor analysis of a test battery that included early first-language (L1) achievement, L1 cognitive ability, second-language (L2) aptitude, and L2 affective measures to predict oral and written L2 proficiency was conducted. The analysis yielded 4 factors that were labeled Language Analysis, composed of L1 and L2 language comprehension, grammar,…

The Linguistic Coding Deficit Hypothesis offers an alternative to affective explanations for second-language learning difficulties and adds another dimension to the role of aptitude. The hypothesis focuses on phonological, syntactic, and semantic components of language and assumes that the individual's control over these components is crucial to…

This article responds to MacIntyre's (1995) critique of the Linguistic Coding Differences Hypothesis (LCDH), which posits that language aptitude is the primary source of individual differences in foreign language (FL) achievement. It defends the LCDH and suggests that difficulties exist with theories that attribute affective and social context…

A discussion of the Linguistic Coding Deficit Hypothesis presents an overview of the theory; describes five prototypes of second-language learners, each illustrated by a distinct language processing profile; and examines how the ability to identify prototypes can help teachers interpret student difficulties and design instruction to address them.…