This chapter focuses on the growth, influence and complexity of policy instruments supporting the data generation governance mechanism. It reviews the historical development of educational indicators to illustrate the difficulty of defining and 'translating' social issues into measurable variables and the possible effects of their use, overuse or misuse. Further, it outlines what is known about the policy functions of indicators, taxonomies and benchmarks as a backdrop for understanding how they have been used to govern education in the European Union (EU). In discussing the growth of benchmarking in the fields of European education, adult education and youth policy, the chapter illustrates the changes in contemporary benchmarking practices, where non-education experts contribute to the development and functioning of 'good' education systems. [For the complete volume, "Europe's Lifelong Learning Markets, Governance and Policy: Using an Instruments Approach. Palgrave Studies in Adult Education and Lifelong Learning," see ED616323.]