This course examines how multiple languages are represented, processed, and controlled in the mind. It introduces major cognitive models of bilingual and multilingual processing, covering lexical access, language selection, cross-linguistic influence, conceptual representation, and individual differences. Empirical findings from psycholinguistics and neurolinguistics form the core of the course, with emphasis on how these mechanisms operate across typologically, culturally, and proficiency-diverse speaker groups. Students will engage critically with theoretical debates and learn to interpret experimental evidence relevant to multilingual cognition.