This paper introduces the basic framework of Discourse Politeness Theory (hereafter, DPT) and analyzes‘inviting behaviors’ in Japanese and Korean quasi-natural conversations, from the viewpoint of DPT (Usami, 2001a, 2002a). DPT has been developed based on the results of a series of empirical research, and it attempts to enable researchers to contrast politeness behavior in languages with and without honorifics within the same framework, while minimizing cultural biases. DPT also attempts to contribute to finding ways to solve problems created by cross-cultural misunderstanding. DPT is based on the core concepts of‘discourse politeness’ which is defined as ‘the functional dynamic whole of factors of both linguistic forms and discourse-level phenomena that play a part in the pragmatic politeness of a discourse’, and ‘discourse default’ which is used for representing the prototypical state of factors both in linguistic forms and discourse-level phenomena within the discourse. DPT consists of the following six key concepts: 1) ‘discourse defaults’, which is used to represent the prototypical state of factors both in linguistic forms and discourse-level phenomena within discourse, 2) ‘markedness of politeness’, 3) ‘markedness of behavior’, 4) three types of ‘politeness effect’, which are positive, neutral, and negative effects toward pleasantness, 5) ‘Discrepancy in estimation value (De value)’, which is the discrepancy between the speaker’s and hearer’s estimation of the degree of Face Threat of the speaker’s act, and 6) ‘absolute and relative politeness’. Examples of‘inviting behaviors’in Japanese and Korean quasi-natural conversations are qualitatively analyzed and explained by using the concepts in DPT. Finally, the contribution of DPT to the study of cross-cultural pragmatics and interpersonal communication is mentioned.