Intergroup conflict continues to be prevalent in diverse societies such as the United States and to have a variety of negative consequences. Research on intergroup ideologies, particularly multiculturalism and colorblindness, has demonstrated their importance in the study of intergroup relations. While research shows that each of these ideologies has positive associations with intergroup attitudes and behaviors, each also has some negative associations, prompting calls for studying other ideologies. This dissertation presents some of the first empirical tests of a newly studied intergroup ideology, polyculturalism, which emphasizes that different racial, ethnic, and cultural groups have interacted and greatly influenced each other and continue to do so. I aimed to build and expand on intergroup ideologies research by (1) directly comparing polyculturalism's associations with intergroup attitudes, intergroup anxiety, and academic self-efficacy in diverse college settings to multiculturalism's and colorblindness' associations with those variables (pilot study, Study 1); (2) further examining polyculturalism's associations with social, academic, and health outcomes, namely intergroup anxiety, sense of belonging at one's university, academic confidence, and motivations for alcohol consumption, which is a health problem prevalent on college campuses (Study 2); and (3) testing a theoretical model of the connections among polyculturalism, social, academic, and health outcomes, by testing possible mediators of polyculturalism's relationships with outcome variables (Studies 1 and 2). Findings for multiculturalism and colorblindness were somewhat mixed, with some positive, some negative, and some nonsignificant associations with outcome variables. However, polyculturalism was consistently associated with less support for social inequality, greater interest in, appreciation for, and comfort with diversity, less intergroup anxiety, greater academic self-efficacy, greater sense of belonging at one's university, and less drinking motivated by intergroup discomfort. Additionally, intergroup anxiety was a significant mediator of the relationships that polyculturalism had with academic self-efficacy and sense of belonging at one's university, and academic self-efficacy was a significant mediator of the relationship between polyculturalism and intergroup anxiety. Taken together, findings highlight that polyculturalism has positive social, academic, and health implications for college students in diverse academic settings, providing some evidence for the proposed theoretical model. It would be fruitful for future work to further investigate polyculturalism.