In this dissertation, I argue that researchers interested in examining the development, maintenance, transmission, and co-occurrence of epistemically unwarranted beliefs would benefit by incorporating, in diverse ways, an important dimension that might prove useful in providing explanatory power in understanding how seemingly unrelated unwarranted claims tend to co-occur. That dimension is social prejudice.To make this argument, I start with a philosophical argument concerning the demarcation problem of separating science from nonscience. Specifically, I argue about separating science from pseudoscience based on the behavior of practitioners rather than the features of ideas or claims. Conceiving of pseudoscience as that which emerges from pseudoscientific behavior has consequences for the treatment of scientific fraud and misconduct in the demarcation literature. This serves as the main focal point of the argument. However, the argument also serves as setting the stage for acknowledging that several major pseudoscientific ideas, including some that are prejudicial in nature, have emerged from within the scientific community and were or even still are considered mainstream scientific theories. Subsequently, I describe both original and replication research examining several factors associated with the contents of peoples’ beliefs. I begin with an experiment examining how people treat positive and negative evidence for a secular and a religious/supernatural claim. This research revealed how people set different evidentiary standards when considering the nature of the claim, the nature of the evidence, and how these considerations intersect with individuals’ own identity. Following this, I describe research investigating socio-cognitive profiles associated with a willingness to share various forms of misinformation concerning the then-novel COVID-19 pandemic, finding primarily that the construct of social dominance orientation is positively associated with willingness to share conspiratorial misinformation. In the final two chapters, I describe a multi-stage project exploring (a) the degree to which explicitly prejudicial and nonprejudicial epistemically unwarranted beliefs covary, (b) underlying socio-cognitive profiles associated with the endorsement or rejection of prejudicial and non-prejudicial epistemically unwarranted beliefs, and (c) peoples’ explicit reasoning behind their beliefs concerning a subset of epistemically unwarranted claims, including prejudicial claims. Findings from this research show robust association between prejudicial and non-prejudicial unwarranted beliefs, that these associations share underlying socio-cognitive profiles associated with belief endorsement. Finally, peoples’ explicit reasoning patterns do not systematically differ when justifying their positions about beliefs that are overtly prejudicial in nature compared to beliefs that are not overtly prejudicial in nature. I conclude with lessons that this research can tell us about how to improve efforts to combat the endorsement and spread of epistemically unwarranted beliefs.