This study is based interaction in institutional settings (job interviews, post-trial interviews with defendants, negotiations between high-school students, telephone conversations between social-walfare officers and parents) and examines the social significance of laughter in dialogue. As an example, two assumptions put forward by Jefferson (1979, 1984) are questioned—namely, that laughter is regularly triggered by something funny and that laughter always has a strong inviting character. The analyses show that, in dialogue, we often laugh alone and not always at things considered particularly funny. Mutual laughter is a sign of rapport and consensus. This is exemplified by the fact that in the job interviews resulting in a job offer there was more mutual laughter than in those involving applicants who were unsuccessful. Unilateral laughter is used to modify verbal expressions or attitudes and can help us in handling ambiguities and tension.