Humans across cultures distinguish intimate, close, or family-like relationships from those that are merely affiliative. Recent work suggests that this distinction is so fundamental that even humans as young as 8 months recognize a common cue of social intimacy: close physical contact. In the current studies, we investigate whether children, ages 6 to 9 years, recognize another hallmark of intimate relationships: emotional intimacy. In Study 1, children used the disclosure of sad emotions, as opposed to facts or happy emotions, as a cue for close social relationships. Interestingly, adults thought that disclosing emotions more generally was indicative of closer relationships. In Study 2, children expected that people in close social relationships would more often disclose sad emotions, but not happy emotions or facts. Again, adults did not distinguish between happy and sad emotions: they thought people in closer relationships would disclose both happy and sad emotions rather than facts. In Study 3, neither children or adults thought that disclosing sad emotions was a way to create social relationships. Together, these results suggest that by the age of six years, children connect close social relationships with emotional intimacy, but that they don’t use it in their planning.