Today we are confronting intelligent machines that can take over our tasks and interact with us socially. Ideally, they will make our lives more effective and fun. However, we also see many cases where machines' behaviors are frustrating, intrusive, or untrustworthy. This course aims to advance students' knowledge and skills in designing conversational interactions for facilitating humans and machines to cooperate and leverage complementary strengths through appropriate modalities that fit the usage contexts.