This chapter develops the Relational Ascription Theory of Ethnic Identity, extending Hsu’s psychocultural paradigm to the analysis of ethnic communities and intergroup dynamics. Drawing on Hsu’s theories of psychosocial homeostasis, dominant dyads, and secondary groups, the chapter constructs a structural framework that explains how minority groups are defined, positioned, and transformed through relational interactions with dominant groups. It contrasts Hsu’s relational approach with mainstream theories of ethnic identity—primordialism, instrumentalism, and constructivism—and reorients the analytical focus from self-identification (“Who am I?”) to group-level ascription (“Who belongs to us?”). Building upon Hsu’s continuum model, this chapter proposes a new model of social structure that captures the varying degrees of institutional openness and cultural exclusion in China, the United States, Japan, and India. This chapter further introduces a threefold typology of Chinese minority cultures—complete assimilation, cultural hybridity, and cultural segregation—and traces intergenerational identity transformations in different host societies.