The National Assessment of Educational Progress (NAEP) measures student science achievement nationally, state by state, and, most recently, across selected urban school districts. Periodically, the framework underlying the science assessment is revised or updated. This document, "Science Framework for the 2019 National Assessment of Educational Progress," is based on the same framework used for the 2009 NAEP Science Assessment. The framework provides guidance on the science content to be assessed, the types of assessment questions, and the administration of the assessment. It also describes the science content and science practices that form the basis for the NAEP Science Assessment. It also discusses item distribution and types of items, as well as draft achievement levels. Finally, it recommends several small-scale, special studies to be considered in conjunction with the science assessment. The framework that guided the NAEP Science Assessments administered in the past was developed in the early 1990s. Since then, several developments have taken place, making it necessary to create a new framework for assessing science in 2009 and beyond. [For "Science Assessment and Item Specifications for the 2009 National Assessment of Educational Progress," see ED507254.]