This monograph deals with variable tag questions. These are utterances with a variable interrogative tag, like It's peculiar writing, isn't it, and the semi-variable tag innit, such as Nice, innit. The aim is to provide a corpus-based, comprehensive semantic-pragmatic typology of British English tag questions. Compared to existing descriptions, the proposed typology is novel in three ways. Firstly, whereas almost all existing typologies are single-layered classifications, the functions of tag questions are categorized into two parallel dimensions of interpersonal meaning: the speech function and the stance layer. Secondly, semantic generalizations are proposed for clusters of grammatical, intonational and conversational properties. Thirdly, the bottom-up description is based on a sizeable amount of authentic, spontaneous conversations, which are analysed both qualitatively and quantitatively.