Developing measures for empirical description and analysis entails several crucial, interrelated tasks. The ﬁrst task is to establish, in concrete terms, the idea or concept to be measured. The second is to consider the most accurate way to measure the concept. After collecting data and creating the measure, another important task is to evaluate the consistency and reliability of the measure. In political science, the study of democracies—regimes that derive authority from citizens—and how they differ from non-democracies constitutes a major area of research. This bibliography covers works that have contributed to the development of empirical indicators of democracy and authoritarianism through their focus on the topics of conceptualization, validity, measurement, and reliability.