This study compared Japanese and Thai younger adults' intra- and intergenerational communication. Both groups linearly increased communicative respect and avoidance, beliefs about politeness, and deference norms as interlocutors got older (from young to middle-aged to older adult). Cross-culturally, the Thais reported more respectful communication to younger adults than did the Japanese, while the Japanese were more likely to be avoidant of communication with middle-aged adults. Both politeness and deference norms were more strongly endorsed by the Thais than Japanese. Via regression analysis, the deference norm positively predicted respectful communication to middle-aged and older adults in Japan, and for young and middle-aged targets in Thailand. Avoidant communication was found to negatively predict conversational enjoyment and satisfaction in both countries.