There is much research on White teachers' negative assumptions and biases about their students of color. Less is known about Mexican American teachers. It is often assumed that there exists a strong understanding of culturally relevant science when both teachers and students are of similar cultural backgrounds. Through the conceptual frameworks of culturally relevant pedagogy and LatCrit, this investigation gave insight into, not only the ways the Mexican American teachers conceptualized culturally relevant science as part of their pedagogy, but also the struggles they experienced with the Spanish language. This study added insight by exploring the interactions of Mexican American teachers and their students in the setting of the fifth grade science classroom. Mexican American teachers experienced struggles and tensions negotiating with intersecting identities. Through an inductive approach, data was collected through pre and post interviews, lesson observations, reflective journals, and school documents from two participants and with the author as participant observer. Findings that emerged included 1) personal tensions with the Spanish language, 2) conceptualized Spanish language tensions in the classroom, 3) a struggle with dichotomous feelings of caring and complicity, and 4) cultural relevance gives way to a curriculum infused with White ideology. The organization of this dissertation began with a description of the data on each participant, the analyzation of the data, researcher's reflexivity, and a summarization. Teachers in this study experienced a rigid dichotomy of feeling proud of their Mexican American heritage yet feeling an allegiance to the colonized Eurocentric patriarchy in power. Likewise, they struggled with promoting English as the dominant language yet implying that the Spanish language was not valued in an academic setting. Implications from the findings are that teachers of color are not very different from White teachers because of the acculturation and assimilation from hegemony of the dominant culture they have acquired in the American education system. Findings from this study exhibited teachers of color being complicit to the hegemony of whiteness in public schools and participated in the assimilation of their students due to the fidelity to the whitened curriculum. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]