Although human laughter mainly occurs in social contexts, most studies have dealt with laughter evoked by media. In our study, we investigated conversational laughter. Our results show that laughter is much more frequent than has been described previously by self-report studies. Contrary to the common view that laughter is elicited by external stimuli, participants frequently laughed after their own verbal utterances. We thus suggest that laughter in conversation may primarily serve to regulate the flow of interaction and to mitigate the meaning of the preceding utterance. Conversational laughter bouts consisted of a smaller number of laughter elements and had longer interval durations than laughter bouts elicited by media. These parameters also varied with conversational context. The high intraindividual variability in the acoustic parameters of laughter, which greatly exceeded the parameter variability between subjects, may thus be a result of the laughter context.