Because levels of party institutionalization may affect the availability of good data, existing datasets have limited reliability and coverage. To overcome these problems, we introduce the V-Dem Party Institutionalization Index, the first global country-level index on the issue. It covers-as of May 2017-173 countries for 116 years (1900-2016). Its geographical coverage, timespan, and conceptual reach are larger than any existing alternative. We offer an additive index that measures the scope and depth of party institutionalization in a country every year. Scope is measured by the proportion of parties that reach a threshold of minimal institutionalization, while the linkages party establish with the masses and the elites define the depth. Exploring a set of well-known cases, we show that: the index has extensive face validity, is consistent across regime types, and is comparable to other established indicators of institutionalization.

A key dilemma facing a military which considers democratization is whether it is confident that civilians will protect its interests. A military’s confidence is a function of three factors: preference alignment with parties (trust), an expectation that allied parties will survive the transition (party institutionalization), and an expectation that allied parties can win power to protect it (party strength). When parties which the military trusts are institutionalized and strong, the military is confident that democratization will not endanger its interests. When these factors are absent, the military seeks to generate credible commitments through bounded democratization—a strategy of setting parameters on open contestation and popular sovereignty to constrain civilians. I test this argument using an original dataset on 525 regime transitions and a novel measure of bounded democratization. I find that when the institutionalization and strength of trusted parties decrease, the military proactively sets constraints on the developing political system.

Much of the literature on populism restricts itself to specific regional contexts. Due to this approach, theories of populism have difficulty explaining cross-regional similarities or differences (such as the prevalence of exclusive populist parties in Europe but inclusive parties in Latin America). Using cross-regional data and exploratory case studies from multiple regions, we provide evidence that the prevalence of populism in a given party system is a function of both party institutionalization and electoral institutions. The combination of these factors we term institutional hostility. In laying out our theory we identify three ways in which populist parties enter party systems and contest elections: populist entry, populist targeting and adaptation, and populist capture.