Abstract: This dissertation examines the language socialization of Japanese male and female two-year old children into ways of acting, thinking, speaking, and feeling as members of their family and society. While previous research on Japanese socialization has primarily observed mother-child dyads within a limited scope of activity settings, the present study examines interaction involving young children and a range of interlocutors in dyadic and multiparty frameworks including caregivers (mother and father) and other adults, siblings, peers, and grandparents, within a wide range of activity settings inside and outside the home including mealtime, play, food preparation, book reading, and visits to the temple. This account is based on longitudinal, ethnographic observations and video recordings of 126 hours of naturally occurring interaction of seven focal children---four males and three females---residing in the Kansai region of Japan. The analysis also draws upon 42 additional hours of data among seven additional Japanese two-year old children collected during preliminary studies in the Kansai region. These data also include questionnaires and daily schedules completed by caregivers, informal interviews, and video playback sessions with adults to probe caregiver ideologies regarding expectations of child learning and development. The analysis focuses on three communicative practices, namely prompting, assessment, and reported speech. The analysis of these practices includes not only the use of verbal language (i.e., syntactic structures, prosody) but also a range of other semiotic resources including body deployment, gesture, eye gaze, and the use of artifacts and space, providing a window through which to view children's socialization into socio-cultural notions of politeness, indirectness, interpersonal relations, harmony, empathy, and authority. The final analytic chapter examines socialization and gender in particular in relation to the three communicative practices examined earlier. By focusing on language socialization practices within the household and community, as well as children's (changes in) participation over time in the activities and speech events that constitute their social world, this dissertation provides insight into how young Japanese male and female children become communicatively competent members of their family and society.