Health literacy has become a national priority in the United States. Although less is known about the rate, outcomes, and costs associated with health literacy globally relative to the United States, the subject has received increasing attention internationally as well. Definitions, conceptual models, and health literacy measures have proliferated in recent years, and consensus does not exist regarding which of these to use. This article offers the following 5 recommendations for setting a research agenda to advance the science of health literacy measurement: (a) develop a comprehensive unified conceptual framework, (b) leverage the measurement knowledge the field has gained thus far, (c) empirically test frameworks and measures using robust research methods, (d) use a tiered approach to measuring health literacy, and (e) advocate for ongoing research and dissemination. These recommendations seek to ensure clarity, rigor, and transparency as part of a systematic approach to health literacy measurement. Once these steps are taken, the field of health literacy can move forward more effectively.