Despite its popularity, signaling a multicultural approach to racial-ethnic diversity is often faced with both positive and negative reactions. In this article, we sought insights into what may contribute to the mixed reactions and why. Drawing on social categorization theories and mindset research, we proposed that an underexplored factor influencing stakeholders' reactions to organizations' diversity approach was their lay theories or mindsets of culture. Specifically, we argued that those who believe that racial-ethnic groups represent unchangeable deep-seated essences-a fixed (vs. malleable) cultural mindset-would react negatively toward the intergroup differentiations and comparisons evoked by multicultural approach signals. Three experiments manipulated organizational diversity approach signals. Results consistently showed that a fixed cultural mindset was negatively related to organizational attraction (Studies 1 and 2) and support for diversity-promoting policies (Study 3) in reaction to a multicultural (vs. colorblind) approach. In addition, Study 3 tested and showed that ethnocentrism, a self-protective mechanism, mediated the negative reactions. Together, the findings support lay theories of culture as a moderating factor that affects reactions toward a multicultural approach. Organizations should take individuals' theories of culture into consideration in their efforts to maximize attraction and support for diversity. (PsycInfo Database Record (c) 2023 APA, all rights reserved).