This book is about one of the most fundamental action sequences found across human societies and socio-cultural contexts: polar questions and their responses. Question-answer sequences are among the most basic building blocks for sequences of action in interaction and are ubiquitous among the languages of the world. Among different types of questions, polar questions are the most common, occurring with greater frequency in all studied languages. This volume presents a collection of conversation analytic studies into responses to polar questions across ten different, typologically diverse languages, in a range of action environments and social contexts. The studies explore different ways in which speakers can respond to polar questions, and the relationships between response design, the action implemented by the response, and the context in which it occurs. Taken together, the studies assembled in the volume present a nuanced view of polar responses as a situated social action.