A new data set provides vital information about the world’s political institutions, from 1789 on a monthly and yearly basis and from 1600 on a yearly basis. The yearly data set from 1600 has more than 90,000 country–year observations, and the monthly data set from 1789 more than 600,000 observations—by far the most comprehensive to date, offering several advantages over other available ones. The data set aggregates specific attributes to create nominal and ordinal rankings of political regimes on a scale of 1 to 1,000. In addition to supporting a rigorous classification of democratic and nondemocratic regimes, it allows researchers to trace institutional variations and to explore alternative ways of aggregating political institutions. As a research instrument, the MaxRange data set permits historically minded scholars to address a number of issues related to the dynamics of political institutions in an unprecedented manner. © 2017 by the Massachusetts Institute of Technology and The Journal of Interdisciplinary History, Inc.