In this article we study the forms and functions of whistling in social interaction. Our analysis identifies two basic forms of conversational whistling, (a) melodic whistling, when participants whistle the tune of, e.g., a familiar song; and (b) nonmelodic whistling. The focus in this article lies on nonmelodic whistles, which come in two contours linked to specific actions: (a) the tonal whistle deployed for summoning (e.g., a domestic animal but also human participants); and (b) the gliding whistle used for affect-laden responses to informings that breach a norm, often ones containing a numerical reference. The pitch contour used on the latter type of whistle matches those found for more lexical sound objects, e.g., oh, ah, and wow. The data base for the study comprises a wide range of audio and video recordings of mundane American and British English telephone and face-to-face conversations.