We sought to examine the fluidity of ethnic identification and test shared reality’s hypothesis concerning the effects of interpersonal relationships on ethnic identification. To investigate the effects of ethnicity of spouse on ethnic identification, Asian-American women (66 from same-ethnicity marriages, 46 from mixed-ethnicity marriages) completed several measures of ethnic identification after thinking about positive aspects of their relationship with either their spouse or their mother. Women in same-ethnicity marriages reported equivalent levels of ethnic identification whether they thought about their mother or their spouse. Women in mixed-ethnicity marriages reported lower ethnic identification when they thought about their different-ethnicity spouse; but when thinking about their mother, they reported high ethnic identification equivalent to the levels reported by women in same-ethnicity marriages. Mediational analyses revealed that, consistent with shared reality theory, shared understanding of one’s ethnic identity with one’s spouse partially mediated the relationship between same- and different-ethnicity spouses and ethnic identification. Implications for theories of ethnic identity and for individuals in mixed-ethnicity romantic relationships are discussed.