A fundamental puzzle in the organization of social interaction concerns how one individual elicits a response from another. This article asks what it is about some sequentially initial turns that reliably mobilizes a coparticipant to respond and under what circumstances individuals are accountable for producing a response. Whereas a linguistic approach suggests that this is what oquestionso (more generally) and interrogativity (more narrowly) are for, a sociological approach to social interaction suggests that the social action a person is implementing mobilizes a recipient's response. We find that although both theories have merit, neither adequately solves the puzzle. We argue instead that different actions mobilize response to different degrees. Speakers then design their turns to perform actions, and with particular response-mobilizing features of turn-design speakers can hold recipients more accountable for responding or not. This model of response relevance allows sequential position, action, and turn design to each contribute to response relevance.