The relation between laughter and speech was investigated by describing the position of naturally occurring laughter in the speech stream of anonymous young adults observed in public places. Laughter of both speaker and audience occurred during pauses at the end of phrases or sentences in over 99 % of the sample of 1200 episodes of laughter, indicating that speech has priority access to the single vocalization channel and that a lawful process governs the placement of laughter in speech. Laughter is not randomly scattered throughout the speech stream. Laughter followed both statements and questions and material that did not seem humorous outside of the conversational context. Speakers, especially females, laughed more than their audiences, but the relative amount of speaker and audience laughter depended on the gender composition of a group. Audiences of both males and females laughed more to male than female speakers. These baseline data provide insights into gender differences, normal and abnormal emotional behavior and define variables for future studies of neuro-and psychopathology.