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 come to understand the nature of these 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.