Language is a rich and complex system that is unique to the human species and marks us as distinct from other animals. Despite being born without it, the vast majority of humans manage to master at least one language in their early years. Furthermore, it is possible that the majority of people speak more than one language (Cook, 2008). During this course, students will be introduced to several theories that attempt to explain how languages are acquired, both first (L1) and second (L2) languages. Students will also consider language learning in terms of specific skills, consisting of vocabulary knowledge, reading, listening, and speaking. Finally, students will investigate a number of differences between people and between language-learning settings that have been shown to influence the acquisition of these skills. In the spirit of inclusivity promoted by the SDGs, research involving non-English languages, including Japanese and Spanish, will be studied. By the end of the course, students will have a greater understanding of how humans acquire languages.