The disastrous aftermath of Katrina brought to light a great rift between Blacks and Whites in the United States. Polls taken shortly after the disaster gave clear indication that many Blacks felt that the response to Katrina was slowed by racism. At the same time, many Whites felt that the residents of New Orleans were to blame for their predicament. To understand the causal role ethnic identity plays in shaping individuals’ perceptions, the present study experimentally manipulated Whites’ social identification and measured their perceptions of the Katrina disaster's aftermath. Our results indicate that White Americans exhibited greater prejudice when thinking of themselves as “American” (an identity seemingly inclusive of Blacks) than when identifying as “White American” or “European American” (an identity that seemingly excludes Blacks). This finding demonstrates a boundary condition to the Common Ingroup Identity Model, such that a dual identity is more conducive to positive intergroup relations when strong racial assumptions exist about the overarching identity.