This Large-N methods case demonstrates how to make use of the Large-N analysis in comparative politics and international relations in general, and in the study of leaders in particular. By using the example of leaders I show how to study a substantive topic in international relations by using many empirical observations to find general patterns in the data set. Moreover, I show how to build a data set properly, which incorporates all leaders in the international system. The data set also includes many other characteristics of leaders that prove to be useful in many analyses that seek to uncover causal relationships between several variables. The Large-N analysis method is an important tool researchers should have at their disposal when doing quantitative research. In other words, it is crucial to have a fit between the research question and the method chosen by the researcher.