Both multiculturalism (which involves recognizing and appreciating differences) and racial/ethnic colorblindness (which can involve emphasizing similarities or individual characteristics) are intended to promote intergroup harmony. Nevertheless, these ideologies can backfire when salient. Although this work has sometimes been interpreted to suggest that dominant group members may perceive salient multiculturalism, and non-dominant group members may perceive salient colorblindness, as threatening, it is unclear what about these interethnic ideologies poses a threat and why. The present article draws upon theories of the self-concept to introduce a framework of Multiculturalism and Colorblindness as Threats to the Self. Specifically, it is proposed that multiculturalism (colorblindness) is potentially threatening to dominant (non-dominant) group members’ collective, relational, and personal selves. Dispositional and contextual variables that may moderate perceptions of threat among members of dominant and non-dominant groups, alternative interethnic ideologies to multiculturalism and colorblindness, and potential future research directions are discussed.