Intonation units have been notoriously difficult to identify in natural talk. Problems include fuzzy boundaries, lack of exhaustivity, and the potential circularity involved when studying their interface with other language-organizational dimensions. This volume advocates a way to resolve such problems: the ‘cesura’ approach. Cesuras, or breaks in the flow of talk, are created by discontinuities in the prosodic-phonetic parameters of speech that cluster to various extents at certain points in time. Using conversation-analytic and interactional-linguistic methodology, the volume identifies the parameters creating cesuras in talk-in-interaction and proposes ways to notate them depending on the researcher’s goal. It also offers a way to study the role of cesuras at the prosody-syntax interface non-circularly, which leads to new insights concerning language variation and change. The volume will thus be of major import to anyone working with natural spoken language, its chunks, its various dimensions, and its variation and change.