The nature of sexual intimacy using lay conceptions (i.e., prototypes) of intimacy and sexual intimacy has been explored. In Study 1, participants listed the features of sexual intimacy and intimacy. In Study 2, centrality ratings of these features were obtained. Although the 2 prototypes were very similar, they each had unique central attributes. In Study 3, central features of both concepts were found to be more salient in memory than peripheral features. Finally, in Study 4, the endorsement of central intimacy and sexual intimacy attributes in real romantic relationships were associated with relationship quality and sexual well‐being, respectively. The nature and function of sexual intimacy is discussed, and it has been concluded that sexual intimacy is best conceptualized as a subtype of intimacy.