This qualitative ethnographic inquiry examines the longitudinal journey of three Asian-American young learners in becoming bilingual/biliterate. With a view of language and literacy acquisition and development as naturally interactive and culturally embedded processes of socialization, I longitudinally investigated three siblings0́9 bilingual and biliteracy acquisition and development in their natural daily setting for six years. I also explored the focal children0́9s situated and reformulated linguistic and cultural identities as second-generation Korean-Americans in the United States. This case study of three children growing up in one immigrant family attempts to capture the multi-layered and interwoven socio-cultural and educational experiences of early bilingual and biliteracy development. Three research questions were examined: 1. What were the language and literacy practices of these three second-generation children in the United States? What kinds of language and literacy events occurred in this family? What factors influenced the literacy practices of these young children in their daily lives? 2. What were the goals and beliefs of the focal participants, parents, educators, and community members about early bilingual/ biliteracy development? What processes did they implement to achieve their goals in daily practice? What were their difficulties and obstacles in achieving these goals? 3. How did the participants construct and negotiate their identities when learning the primary language of the society they lived in while maintaining their heritage language? Vygotsky0́9s (1978, 1986) social-constructivist theory explaining early learning and development as a socially collaborative procedure, and Wenger0́9s (1998) theory of communities of practice were used as the basis on which to investigate bilingual and biliteracy practices within and across diverse communities, including the home, school, church, playground, heritage language school, and neighborhood. These socio-cultural theoretical frameworks fit the nature of my inquiry because of their focus on socio-cultural influences and reflective discourses in early bilingual and biliteracy development as well as identity formation of early bilingual/biliterate learners within and across different social settings. Based on these theoretical frameworks, extensive qualitative data from multiple sources was collected in the following forms: in-depth interviews, participant observation, document review, and informal/narrative assessment that measured focal students0́9 bilingual and biliteracy development in two different socio-cultural contexts. In order to analyze various situational discourses; social and educational activities; and written artifacts and documents, I coded both oral and written data and looked for emerging themes. In each chapter, major characteristics and issues are explored, such as similarities and differences among all participants within one family context and across each individual characteristic in the course of acquiring and developing another language and literacy as second-generation immigrant children. The findings were generated from comparative, cross-case, and holistic analysis of multiple sources of descriptive and qualitative data (Yin, 1989). This study makes the daily practices of young second-generation bilingual/biliterate/ bicultural young learners visible as I look into their socio-cultural influences over the course of six years. Forming bicultural and bilingual/bliterate identites via daily heritage linguistic and cultural experiences, as well as maintaining linguistic and socio-cultural motivations, are vital. High-quality dual immersion programs including heritage language/cultural schools should be available to every young diverse learner. Continuous longitudinal research on those programs along with family literacy research for specific language and ethnic groups should be systemized for early multi-lingual/literate and multi-cultural education in the United States.