This course examines the effects of cognitive (e.g., aptitude, working memory) and affective differences (e.g., motivation, L2 anxiety) on second language acquisition. Students will be provided with a foundation in quantitative analysis and come to understand the nature of individual differences via empirical studies on learners of French and the use of assessment instruments including questionnaires and on-line tests. Particular emphasis is placed on students' ability to discuss between-learner differences in comprehension and production, identify relevant individual differences capable of explaining such variability, and conduct their own individual differences research.