How accurate are people’s stereotypes about groups? And how accurate are people in knowing what others think of the groups they belong to? The goal of this chapter is to provide an overview of conceptual and methodological approaches to studying accuracy in people’s attitudes about in-groups and out-groups, and to provide a brief review of empirical findings that address such accuracy. I focus on two central questions that scholars have addressed: One, are people accurate in their judgments about groups? And two, are people accurate in reading what others think about groups to which they belong (i.e., meta-perceptions of attitudes about groups)? I first discuss methodological and conceptual approaches to studying group-based attitudes, including a discussion of the process through which a valid truth criterion is selected, the different ways in which the relationship between the truth and the judgment can be operationalized, and the level at which accuracy is measured. I then review findings from research on accuracy of group-based attitudes using a motivation-based framework to understand why perceivers might be accurate or inaccurate in their judgments. Finally, I propose several avenues for future research, with an emphasis on research designed to provide evidence of the process through which perceivers become accurate and biased in their own attitudes about groups and their perceptions of others’ attitudes about groups.