Laughter is a pervasive human behavior that most frequently happens in a social context. However, data linking the behavior of laughter with psychological or social outcomes are exceptionally rare. Here, the authors draw attention to shared laughter as a useful objective marker of relationship well-being. Spontaneously generated laughs of 71 heterosexual romantic couples were coded from a videorecorded conversation about how the couple first met. Multilevel models revealed that while controlling for all other laughter present, the proportion of the conversation spent laughing simultaneously with the romantic partner was uniquely positively associated with global evaluations of relationship quality, closeness, and social support. Results are discussed with respect to methodological considerations and theoretical implications for relationships and behavioral research more broadly.