This paper presents a new measure polyarchy for a global sample of 182 countries from 1900 to 2017 based on the Varieties of Democracy (V-Dem) data, deriving from an expert survey of more than 3000 country experts from around the world, with on average 5 experts rating each indicator. By measuring the five components of Elected Officials, Clean Elections, Associational Autonomy, Inclusive Citizenship, and Freedom of Expression and Alternative Sources of Information separately, we anchor this new index directly in Dahl's (1971) extremely influential theoretical framework. The paper describes how the five polyarchy components were measured and provides the rationale for how to aggregate them to the polyarchy scale. We find Department of Political Science, Aarhus University, Aarhus, Denmark that personal characteristics or ideological predilections of the V-Dem country experts do not systematically predict their ratings on our indicators. We also find strong correlations with other existing measures of electoral democracy, but also decisive differences where we believe the evidence supports the polyarchy index having higher face validity.