The National Assessment Governing Board (NAGB) periodically updates National Assessment of Educational Progress (NAEP) frameworks in each subject area in order to ensure that the assessments reflect current thinking about teaching and learning. Given the heightened interest in NAEP results occasioned by No Child Left Behind (NCLB), it has become increasingly important to establish sound policies and procedures for reporting results of NAEP assessments based on new or modified frameworks. The purpose of this paper is to recommend guiding principles, studies, and decision-making processes that can assist National Center for Education Statistics (NCES) in determining whether the results generated by an assessment based on a new NAEP framework can be validly reported on the same trend line as previous versions of the assessment.