For the past century, standardized testing in the United States has been a measure of school success on both the individual and organizational level. A seemingly benign measure, such testing has informed the allocation of resources and placement of students in coursework commensurate with their perceived abilities. However, I argue that standardized tests serve a more malicious function in schooling by systematically erasing epistemologies that differ from the dominant society. Tracing the history of U.S. standardized testing in the 20th century, I conclude that such tests have marginalized low-income students and students of color, and will continue to do so as long as they are heavily relied upon as measures of intelligence and success.