AbstractIn this paper, we propose a scheme for annotating utterance-level units in Japanese dialogs, which emerged from an analysis of the interrelationship among four schemes, i) inter-pausal units, ii) intonation units, iii) clause units, and iv) pragmatic units. The associations among the labels of these four units were illustrated by multiple correspondence analysis and hierarchical cluster analysis. Based on these results, we prescribe utterance-unit identification rules, which identify two sorts of utterance-units with different granularities: short and long utterance-units. Short utterance-units are identified by acoustic and prosodic disjuncture, and they are considered to constitute units of speaker's planning and hearer's understanding. Long utterance-units, on the other hand, are recognized by syntactic and pragmatic disjuncture, and they are regarded as units of interaction. We explore some characteristics of these utterance-units, focusing particularly on unit duration and syntactic property, other participants' responses, and mismatch between the two-levels. We also discuss how our two-level utterance-units are useful in analyzing cognitive and communicative aspects of spoken dialogs.