The communicative act of non-acceptance expresses the speaker's intention to deny, reject or disagree with a communicative act. Regarding its sequential status, a non-acceptance is a responsive act par excellence, and from an interpersonal perspective it can be assigned the status of a face-threatening act. While its responsive format does not seem to cause any severe communicative problems in intercultural communication, its face-threatening potential makes it a prime candidate for intercultural miscommunication. The goal of this paper is to systematize the contextual constraints and requirements of a non-acceptance in a dialogue frame of reference based on the dialogue act of a plus/minus-validity claim (Fetzer 2002, 2004), which is anchored to the Gricean cooperative principle (Grice 1975), Habermas' theory of communicative action (Habermas 1987), and Brown and Levinson's theory of politeness (Brown & Levinson 1987). The pragmatic premises of intentionality, rationality, and cooperation are supplemented by the interactional-sociolinguistic universal of contextualization (Gumperz 1996). The dialogue framework allows for a comprehensive examination of culture-preferential modes for the realization and contextualization of nonacceptances and possible perlocutionary effects, illustrated by excerpts from German, British and intercultural German-British political discourse.