One of the most remarkable democratic developments in Europe in recent decades has been the empowerment of the only directly elected supranational assembly in the world: the European Parliament (EP). We first review the development of the legislative powers of the EP vis-à-vis the other European Union (EU) institutions, discussing the theoretical models of the power of the EP and the main empirical methods that have been used to evaluate these models. We then turn to the impact of the growing power of the EP on political organization and behavior inside the legislature. We demonstrate that the “electoral connection” is weak and discuss what this means for understanding legislative politics in the EP. The concluding section demonstrates differences in behavior across policy areas, which have received scant attention, and suggests avenues for further research.