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.