In conversation analysis, questions are explicated in sequential terms. They constrain relevant types and forms of response in the next turn, and the specifics of response construction provide resources that inform how questions and their actions and constraints are understood. This article aims to contribute to our cross-linguistic understandings about question-response sequences by examining responses to polar questions in Korean conversation. It examines two forms of affirmative responses, "unexpanded" and "expanded." In unexpanded responses that consist of an interjection "yes" alone, respondents do nothing more than a mere affirmation and treat the question as simply seeking (re-)confirmation about the matter that had been conveyed in prior talk. By contrast, in expanded responses that involve additional components after an interjection in the turn, respondents not only affirm the matter at its face value but also provide elaboration addressed to the inferred purpose or intention that may lie behind the question.