There is a shocking dearth of scientific certainty about how to assess racial bias in policing. Specifically lacking is an examination of the causal relationship between officer psychological attitudes and their interactions with minority suspects. Do officer racial attitudes lead to more racially biased police behavior? Why do we, as psychologists and scientists, know less than we should about psychological attitudes and their effects on police behavior in the field? To answer this question, we first review what researchers have learned given the available types of existing data: crime data, officer data, and public opinion data. Next, we discuss how insufficient access and lack of rigorous design have detracted from thorough research on racial bias in policing. Finally, we detail how new opportunities for social scientists have the potential to overcome these barriers and conduct rigorous psychological research on equity in policing.