Knowing and speaking more than one language is the everyday norm of people living in much of the world including in multicultural cities like Toronto. Via an in-depth introduction to the cognitive and social underpinnings of bi- and multilingualism including second language acquisition, this course provides answers to questions such as How do bilinguals/multilinguals differ from monolinguals in the ways that they process and use language? How does acquiring a language as an adult differ from when we are children? How do an individual’s language repertoires interact with those of their peers and local community?