This paper explores the social and cultural idiosyncrasies of Japanese addressing forms and issues in teaching such addressing forms to American English-speaking learners of Japanese. It argues that one of the most difficult aspects of acquiring Japanese addressing forms is caused by certain cross-cultural and cross-linguistic differences. This study investigates such differences by comparing and contrasting Japanese and English addressing forms for the similar speech contexts and interpersonal relationships. Based on the research findings, it further argues that the key to the acquisition or native-like use of Japanese addressing forms is to understand the essential Japanese social and cultural aspects in language use. The study focused on two groups of Japanese addressing forms, one for addressing family members within the speaker's family situation and the other for introducing the speaker's family members to non-family members in various formal and informal spe! ech situations. The study was based on a questionnaire regarding the natural use of the English addressing forms in similar speech situations by American college students. The results were compared with some most commonly occurring learner errors in using Japanese addressing forms, and those learner errors are discussed in terms of potential cross-cultural and cross-linguistic interference. Based on the analysis of the learner language data, the study offers several Japanese language pedagogical implications: (1) Learners' understanding of Japanese language-specific forms is not sufficient enough for using them in a socioculturally acceptable manner. (2) Learners' inappropriate use of Japanese addressing forms is mainly caused by their native social and cultural transfer. (3) Learners' understanding of certain social and cultural aspects in language use is an indispensable part of foreign language teaching. The study concludes that the sociolinguistic study of language use s! hould be an important part of Japanese language teaching and learning.