State testing programs today are more extensive than ever, and their results are required to serve more purposes and high-stakes decisions than one might have imagined. Assessment results are used to hold schools, districts, and states accountable for student performance and to help guide a multitude of important decisions. This report describes commonly unrecognized sources of error variance (or random variations in assessment results) and provides actions states can take to identify and reduce these errors in existing and future assessment systems. These "errors" are not mistakes in the traditional sense of the word, but reflect random variations in student assessment results. Unlike the technical report on which it is based, this report is written for policymakers and educators who are not assessments experts. It provides an explanation of the sources of error variance, their impact on the ability to make data-based decisions with confidence, and the actions states and their contractors should take as quickly as is feasible to improve the accuracy and trustworthiness of their state testing program results. Peer Review Panelists are appended. (Contains 6 footnotes.)