The responsiveness of democratic institutions is a topic of fundamental importance to researchers, citizens, and decision-makers. Research is hampered because existing datasets are scattered, unconnected and inconsistent. Our proposal aims to assemble a unified and cross-indexed resource freely accessible on the Internet. This database would be uniquely effective since it would be a time series dataset of European politics. The database will have homogenized coding across all datasets within it, and all datasets will be richly cross-indexed. It would be comprehensive because it would encompass data on the preferences of the European electorates, political parties and governments, as well as past election results, and complete legislative outputs. It will allow researchers to use large-N statistical methodologies to empirically test models of dynamic representation in a multilevel system of governance.