This chapter provides an overview of health literacy measurement initiatives with a focus on the European Health Literacy Survey (HLS-EU) - describing where measuring population health literacy started, where it currently is, and providing an outlook to the upcoming European HL survey. In the first part of the chapter, the methodology and the main results of the initial HLS-EU study from 2011 will be introduced. In the second part the worldwide impact of the HLS-EU study will be mapped. Many publications and studies used the HLS-EU instruments in the original or few in an adapted way to measure comprehensive health literacy - in many different settings and in diverse countries. Finally, the chapter ends with an outlook to the M-POHL and HLS19 initiatives of WHO-Europe which are intended to advance HLS-EU as well as the measurement of population and organizational health literacy in a more coordinated, standardized, and institutionalized manner.