This chapter describes the research methods psychologists use to study prejudice and discrimination. Researchers formulate hypotheses about the factors that affect prejudice and discrimination, and decide how to make the abstract concepts used in theories (hypothetical constructs) into concrete operational definitions that can be measured and manipulated in research studies. The measures used in research have the two necessary qualities, reliability and validity, which can be assessed to determine a measure’s quality. The most common types of measures used in research on prejudice and discrimination are self-reports, unobtrusive measures, physiological measures, and implicit cognition measures. Researchers use several research strategies to collect data, including correlational studies, laboratory and field experiments, ethnographic studies, and content analysis. Based on their data, researchers draw conclusions about the extent to which the data support their hypotheses and the implication of those data for theories and practical applications. Because every research study has limitations, researchers conduct additional research to verify their results and to determine how well those results generalize beyond the context of a particular study.